Okay this is my take on the names and hidden meanings! I'm probably wrong but hey! My media literacy needs worked on!
Rue: a quick look up shows that it means sorrow, regret and "A bitter regret for a past action or event" Now that is clearly supposed to be dedicated to the apple incident right?? I mean he ate the apple he wasn't meant to?? BUT THAT'S TO OBVIOUS FOR LIL OL ME AND I HAPPENED TO READ SOME OF THE OTHER STUFF! >:3 What if it's his regret about how he treats his men? In an info-dump-thingy it's mentioned that he's trying to do better for those he cares about! It's PROBABLY about the apple incident though, just a fun "What if?"
Zero: uhh- probably he's 0% a good person! (Joking joking mostly) if you look up symbolism for the nickname Zero it shows a lot about anonymity, insignificance, nothingness, and a fresh start! Now, these can tie back to Rue; considering how canon the Joku Dreamtale story is to this AU, Rue definitely was insignificant in the eyes of the villagers as the guardian of the negativity apples and negativity in general. Zero PROBABLY represents Rue's—or technically Zero's since Rue was out cold for forever—new start as the king of negativity.
Helem: Now this one's adorable! It's Arabic for dream, and is also the name of the "oldest LGBT+ rights organization in the Arabic world" (yes I used Wikipedia as a resource sue me). So OBVIOUSLY this is about him being gay! Right? Well maybe? I'd prefer if that's not how I ended it with "He's gay and that's all there is to it! :D" So let's look at the translation, dream, I mean his whole entire canon story is him being forced to join Chara under the code manipulation of him "wanting something new". His canon story is him going from one abuser to the next (Chara to Nightmare, since its clear that Zero has no particular care for Killer based on what I've read/seen). I think its safe to assume that Helem is Dream/hope of a better life (which I'm also taking from his character design, he dresses like he's a bit more optimistic in your AU)
Purge: Allow me to pull up Webster's dictionary real quick! Purge (Verb.): (1)To clear of guilt, (2) to make free of something unwanted. There are other definitions that I don't think are necessary in this instance, but I think going with definition one is the best if we're going to follow in Helem's trend of hope. In Dusttale Dust is overcome with guilt of killing his friends, his FAMILY and hurting them, even if he believes he was saving them pain and torment from the hands of the human. (Fun Fact of the day, in canon Dusttale I believe it was confirmed that Dust only killed them once because if he did he would go absolutely insane and be consumed with guilt.) So his name Purge would be him overcoming and coping with his guilt throughout the story and "purging" it from his life with Helem and Ardor (possibly Rue once he learns to care).
Ardor: it's a word used to describe passion, enthusiasm, devotion, or the warm feeling of someone! This name falls right in line with the other names! Now you might call me a larper or someshit, but I haven't read him in the Tumblr page yet, I haven't seen him in the comic, and I don't remember if he showed up in the story or if I'm getting it mixed up with another one- ANYWAYS this one differs from canon the most, to a more fanon version of Horror where he takes on a more caring version of Horror, his name indicates that he probably is more of the "mother hen" of the group, he would care deeply about his group and probably forces them to eat. In fanfiction he is the most stagnant of the MTT, so I'm not going to dwell on him to much!
Cinnamon: You won't catch me spelling his name anymore than I have too! And I saved orange just for him! Now this character is new: haven't seen him anywhere and I don't even know exactly which side he's on yet, so I really only got his name and Fell!Ccino to work with! NOW Cinnamon is known for its overwhelming taste and slight "spice", the spice is a type of inner bark. Now his name checks out because Ccino is a fluffytale monster (if I'm not mistaken) who owns a cafe filled with cats, and cinnamon goes in coffee and pastries. NOW he probably doesn't wear his heart on his sleeve like canon Ccino, but also is a lot more trusting than Fell. He probably has a bit of a kick and "duh" attitude while still being there for his friends and listening to them as they need him. I'm imagining he's on Zero/Rue's side due to him being a Fell!Ccino, but I could also see him in the Omega timeline, but extra grumpy.
True: This probably is about Swap and his need for justice and knowing the truth, now Im choosing to take this in a more pessimistic way unlike the rest of Nightmares gang. I believe that the truth he is searching for will not be what he likes. We already know he has opinions on Dream and Ink, and how they function with the multiverse. Now we already know the gang isn't what Truth will be expecting, he expects a bunch of killers and murderers, which as we see above, simply is not what they are. I believe that Truth here—as our protagonist—will be the key to getting all of them to be better. (ICL at this point I got this swap confused with another and it's almost midnight and I refuse to correct any mistakes, anything that includes the gang just add in True)
Nemo: this one is by far the easiest, and I know that this one was either a pain in the ass to come up with for Ink or came to you incredibly easy. This is a reference to Finding Nemo, but specifically Dory, who has short term memory loss: like Ink here. I refuse to leave it as just that though and would like to think that True is actually Nemo, as in Ink is travelling the multiverse with Dream to find him, and pull True out of "tantrum" or something similar.
Muse: now this name is ironic to the canon Error as the definition of muse is either a guide, a thoughtful thought-thing, or a deep thought. I want to believe that we're going with a guide since that's a well known definition, but thinking something in a thoughtful way makes more sense. With all his time alone he probably spends a lot of it thinking and listening to the voices, he has to have learned to be more reflective, now that doesn't mean he stopped destroying AUs, I just mean I think there's a redemption arc somewhere in him
Grim: Wish I could say I saved the best for last, but in all honesty I just forgot to do him- Grim means foreboding, depressive, or stern. These could represent how oppressive Grim truly is to True, and even others. Positive emotions are not the only thing that matters, and pure joy is almost as bad as pure sadness. Grim in this fic won't care about the individual and what they need, just that they're smiling and happy.
But. There's another meaning. Grimm's fairy tales, made by the Grimm brothers. They wrote classic stories such as Little Red Riding Hood, Cinderella, Rapunzel, The Frog Prince, and most famously: Hansel and Gretel. Now I want you to ask yourself, what do these all have in common? No, not the Disney movies, the books. They mostly have unhappy endings, the characters die, they're kidnapped, hurt, etc. Etc. I believe this is going to foreshadow Dream and Rue's fates, at LEAST Dreams'. Wouldn't it be funny if we finally had a Dream die in a fanfic? :3 No, Dream won't die, that disrupts the balance of positivity and negativity. BUT he will probably end up losing and having to go into hiding or something.
I might be so wrong on many of these or didn't look deep enough into them, but eh, I'm out of analyzing juice. By far my favourite name is Nemo just because of how dumb it is unlike all the others, followed by Helem, I like how it connects Killer to his Arabic roots! I think this will be an interesting fic to read once it's more published!