Some examples of the differences that (positively) most caught my eye:
EN: "Only those who belive in the false king will remain here and face death"
FR: "Only those who believe in this imposter of a king will remain here and die at my hands."
The English translation makes this statement very..passive, almost? When we see Enryu specifically killing Zahard's followers once they take up the gauntlet he threw down by denouncing Zahard. At the end of the day it's personal taste, but I do prefer the emphasiz on himself as the acting party in a character that is already as sparse in actual character moments as Enryu. I also think his label of Zahard sounds slightly more contemptuous in the second one, which is anothe plus to me.
Traumerei's ultimatum to Wangwang
EN: "Yes. What difference will it make if I know how some insignificant creature would feel? Did you expect me to show love and mercy? And that to a mere dog? [...] Well, give your body to the canines that are running to you now and die with as many scratches on your body as their number. Then I'll show mercy as you wish."
FR: "Yes. Why should I concern myself with the feelings of creatures more insignificant than a grain of dust? Don't tell me you expected love and compassion from me, and that for a simple dog? [...] Let's see. If you leave your body at the mercy of all these dogs that are currently descending upon you...and let them mark it with as many scratches as there are individuals in their ranks, then this death will deserve my mercy."
Just colder all around, imo (plus the English TL spamming the whole "insignificant creature" just a bit too rapidly in Traumerei's dialogue in that chapter in particular, so anything that breaks that up a little is good in my book). The more mocking "don't tell me", the comparison of Wangwang and his children to beneath even a speck of dust to Traumerei (that I also remember from an English fantranslation back in the day). While it does depend on what you chose to go with (the potentially better fit at the end may well have been "pity"), I chose to go with "mercy" for the closed loop this makes with Traumerei's mention of the "mercy of all those dogs" (that we know HE is controlling the actions of). Traumerei also comes across as less acquiescing in his closing word there, positioning himself as the final arbiter of mercy imposing his conditions rather than the guy kindly being willing to honor Wangwangs wish, which also feels more fitting to me.
Zahard's speech to Khel Hellam and the Hidden Grove
EN: "You're here. [Khel Hellan:'...Who are you?'] Let me ask you something. What am I to you? I was the first one to climb the Tower. I was the greatest Fisherman in battle. And I pioneered a civilisation of mutual understanding among the people of the Tower. But you probably know me best by a different word. The word "King". [...] What a fool. Are you that sure of the future you saw? You're so full of yourself after getting just a little glimpse of destiny that now you think you can predict everything. And yet you're blind to the truth staring you right in the face. You'll see for youself once we start fighting whether I'm really the king or not."
FR: "There you are. [Khel Hellam: 'Who are you?'] Well...That's the question I wanted to ask you. What am I to you? I'm the first traveller who climbed the Tower. I was the best Fisherman on the battlefield. And I'm also the pioneer who passed on to all the beings in the tower a civilisation that enabled them to understand each other. But the term that describes me and that you probably understand best is certainly that of “King”.[...] What a ridiculous guy. Are you convinced that there can be no mistakes in the future you have seen? Your ability to foresee fate makes you proud. You think you can predict anything. So much so that you have become blind, refusing to believe the truth that is right in front of you. In that case, confront me, and you can confirm it for yourself. You will know whether I am really the King or not."
This might arguably one of the "smaller" ones but I do enjoy how it basically confirms my interpretation of the more ambiuous English version, where Zahard inquires after the Hidden Groves views on him and his many potential titles and accomplishments, rather than just talks down to them à la 'What do you take me for' that many people seem to take it as. I also just like the segment on precognition better, as it feels more elegant to me in its structure (and less colloquial). Again, personal preference.
Data Zahard's words to Bam
EN: "Take it. I want to show you to the me on the outside. You have to meet the outside me. It may be hard right now, but if you grow more...You may even be able to give the me on the outside a new experience too. So I'll let you go. [...] Little monster. [....] Let the me on the outside taste the thrill of adventure once more-"
FR: "Take it. No matter who you are, I want to show you to the outside me. You absolutely must meet him. It will be difficult for now, but if you evolve even more... You might be able to bring him something new. I think it's destiny. That's why I'm going to let you go.[...] Little monster. [...] And force the me from the outside to resume the adventure and…"
That's some very blunt irony that's missing in ENG with the whole "no matter who you are" and the huge "destiny" plot point of Bam as Zahard's prophesized killer, as well as a different vibe in data Zahard's wish to his outside self (with more potential lore implications...), with a continuation of their adventure rather than a completely isolated new one, as a bit of enrichment only. I also like that it makes data Zahard look a bit harder on his outside self to get off his throne again haha.
Outside Zahard's data fragment
EN: "You look...Strange...Those golden eyes...I thought I killed you before. ..Son of Arlene. I can tell just from looking at your eyes. I don't know how you managed to come back to life but fate is really toying with us...Son of the women I loved more than anyone. I didn't think I would get to kill you again with my own two hands...Don't be too sad. I'm going to find everyone here and on the train, and everyone you've ever run into. Then once I've killed them all I'll send them to you. So rest in peace."
FR: "You...That's strange..Those golden eyes...But I killed you. Son of Arlen. I know it just by seeing these eyes. I don't know how you managed to come back to life, but fate is really playing with us. Child of the woman I loved most. I didn't think I'd have to kill you again with my own hands...I'm going to find everyone on the train and on this floor and everyone you've met so far. When I've killed them all I'll send them to you. Go in peace."
Mostly the same, but with some minor but crucial (to me, someone hypersensitive to every minute detail that migth shift the perception of Zahard) differences. The biggest one obviously the implied relish of the ENG at "getting" to kill Bam again, whereas this is explicitly a unwelcomed necessity in FR (something which I obviously prefer, even if only for the reason that Zahard killed him for the purposes of staying dead the first time). Zahard also comes across as a bit more genuinely baffled in the FR to me with the short "But I killed you(/I killed you though") as an alternative phrasing (..?? implied). And again, probably pretty minor to most but a welcome difference to me, given how much fanon tries to reduce Zahard to an Arlene obsession, the more subdued "woman I loved most" than "woman I loved MORE THAN ANYONE" (which, hey, might well be true, but I appreciate toning it down nonetheless, given how much fandom cannot shup up about it).
EN: "What are you doing? Hey."
FR: "What are you doing? Other me."
EN: "...An adventure, huh? That's right, embarking on an eternal adventure- if that's my fate, I have to accept it. However. Since that day when I began to see all causes and effects from the same height as god....I found out how to play around with fate. Cruel fate."
FR: "It's...an adventure? That's right, it's the beginning of an eternal adventure. If this is my destiny, I have to accept it. Only, since that day when I was able to look at all causes and effects...From the same height as a god...I learned to play with fate. And fate is cruel."
Arguably the most minor one on the list, but I feel like FR makes it clearer that the data of outside Zahard is responding to the "adventure" data Zahard meant by pointing at Bam * shrug * Also potential lore implication by refering to a more general "a god" rather than the one..?