I've posted this to twitter some time ago, and have seen comments that this is extremely OOC on all accounts. I'm figuring that since the tumblr format allows me to do long-form comment, I'll go ahead and outline why I decided to make this the way I made it.
I'm starting with the evidence that we have in canon: in the epilogue RWBYJ followed Raven into her portal to Qrow in Shade Academy despite Shade having been in view, to which they could have just walked there in no time.
1) Raven joined the fight against Salem (as corroborated in RWBY beyond).
2) Raven instantly tried her portal to Yang when it reappeared.
3) RWBYJ felt that Raven was trustworthy enough to follow her into what could have otherwise been a trap. Their trust towards her should not have been there based on how they had last parted ways.
Based on these statements, here was my thought process:
Raven has changed since the last time she was on screen. If she hadn't, then she would still be avoiding everyone and be off the map. The last time she was on screen was when Yang tore into her verbally, rubbing her face into her erroneous notion of strength. When she made Raven understand that strength ≠ power; that strength was doing the hard thing (the right thing!) despite being terrified. Which is how now, with kingdoms entirely destroyed and relics in Salem's hands, when the situation’s never been worse and despite having been terrified of Salem most of her life... Raven joined the people fighting this last-ditch effort against Salem. Raven could easily have elected to do as Hazel had done “if you can't beat them, join them”, that would have made sense with her previous cowardice, but she didn't. The same can be said about the fact that she instantly tried her portal to Yang when it reappeared: she didn't keep running away from Yang. Raven changed, so she is doing the right thing despite being scared. Her having changed was how she was both willing to and capable of facing Yang again.
So, if canon evidence shows us that Raven did change, then it follows that for RWBYJ to follow her into her portal, she must have said/did something that conveyed that she had changed.
This is how I opted to have her show regret. I don't believe that Raven could be genuine enough to say anything like ‘I love you’ or ‘you were right’ to Yang (maybe someday in private, but her ego would prevent her to say it in front of others). But ‘I’m sorry’ is already something that she has said. Sure, she said it as she ran away, leaving Yang with the burden of the relic, but she said it. I also thought it was important to have Raven's dialogue be brief, because I'm not sure she's all that great at expressing her emotions. Brief lines touching on how she's here (her semblance allowing her to know they were back), why she's here (her jumping at a shot to start fixing what she regrets most and thought had become forever out of reach: her relationship with Yang), and her outlook having changed (her respect for what they did by calling them heroes), could work in making RWBYJ trust her imo.
The last of the criticism I've seen is that Yang thinks of Summer as her mother, not Raven. Which I agree is true, but that doesn't diminish the fact that Yang has always called her Mom, even in V5 as she sees Raven for what she is. She also has searched for her all her life, from the moment that she knew that Summer wasn't her biological mother. Yang doesn't love Summer any less or see Summer any less as her mother for wishing that Raven hadn't rejected her or for yearning for Raven, which she does; Yang wouldn't call Raven Mom nor would she have searched for her all her life if it wasn't the case. I didn’t make Yang say anything back because I don’t think her conflicting feelings following all that she found out about Raven and how they parted ways could be put into words so easily as to answer her right away, but it is why I made her hug Raven back.
It's also that... I really believe that, when it comes down to it, RWBY is a show about hope. The ultimate question that the story leads to is whether or not humanity deserves to be saved (when/if the relics are brought together and the brothers reappear). Sure, not all characters can see redemption, but many do find their way back: Ilia, Hazel, Emerald, Whitley, even Neo realized she needed to change — she at least learned to let go. And the way our main characters react to those who do show regret for the past wrongs is always a compassionate outlook. Again, even Neo who didn't join them, they left her with wishes that she can find peace and be reborn as someone who isn't consumed with hate and revenge. That's compassion if I ever saw it.
So... Raven, who has demonstrably grown into a better person, should also be regarded with some compassion, and she should be allowed to work towards mending what can be mended. This is all why RWBYJ accepted to trust her & why I think that, although Yang was hurt and angry, and would be entitled to outright reject Raven... i think that, if offered the words that I wrote out in this comic, she would accept that olive branch and those feelings from Raven, as they are what she's always wished for. It's in line with hope as a theme.
So anyways, I hope this summarizes everything well enough. I know it's a bit all over the place.