I have a few more suggestions and concerns I'd like to mention.

1. During the bite night scene when you let Astarion drink more, Tav doesn't have a bleeding neck, like they do after using the first persuasion check, so it's clearly a bug.

2. Why is there no explanation why Astarion thinks biting an elf during their trance is a good idea? From what I've read elves are fully aware of their surroundings while in that state, so of course they'd sense his presence and confront him. I know he at least has a poor excuse in Karlach's case that he's so hungry that he conveniently forgot about her untouchable condition.

3. I've mentioned it already in a couple of threads, and I'll mention it here too: I would love there to be a scene before the point of no return where you spend some time together with your partner, comment on your journey so far and prepare for what's to come. It's just strange and sad there are no camp events after completing your LI's story. With the Ascendant we could go to the Crimson Palace and start making plans for the future, talk about redecorating the interior, etc. With Spawn Astarion we could go watch the sunset or sunrise together, like it was suggested by Hula Noob in their thread in the feedback forum.

4. As was discussed in another thread too, when Ascended Astarion urges you to
take control in the ending choice, we should have an opportunity to have a short discussion with him about it to let him know what we are planning to do. Likewise, I'd like there to be another one in the epilogue where we talk about the aftermath. Right now, it looks very awkward that he asks us to do something, we don't communicate with him, do the opposite and he has nothing to say about it afterwards. He completely forgets about it after the dock scene. There is only random chance in there to hear him say he's glad the "stupid worm" is gone from his head. Compare it to Minthara who also wants to usurp the brain's powers and does have a chat with Tav about them abandoning that idea post final battle.

5. I would have liked Astarion to have a reaction to our dialogue when we lie to his brethren in his support when they try to abduct him. He takes notice of you telling them they can take him if they want to, so it would be nice if he could express extra gratitude when we back him up. We also don't have any dialogue here reinforcing our stance that we'll help him ascend. There are only neutral and negative responses.

6. It's not specific to his romance, but I'd still like to say that I really like the menacing way Astarion's eyes look during ascension. It would be cool if his eyes would glow like that again when he enters combat to show him utilising his new powers.