As for what I think is good - that he is free. Even with the spawn restrictions, he is still free to do and decide,what he wants. With the Ascension, he is basically tied to Mephisto, He made a devils deal. So he might be free now and if lucky for a long time, but when he dies, he will be Mephistos bitch. And Mephisto Likes to use souls for his experiments, so I see and fear a new cycle of abuse. That of course is speculation based on my DnF knowledge of Mephisto and devil deals in general. Maybe the 7000 victims buy the afterlife freedom for the one ascending too, I don't know. But neither does Tav/Durge or Astarion.
Astarion is free of Cazador without the ritual. That's it. Ascended is free from Cazador + many other things, I won't repeat myself.
Excuse me, but why do you like to use the word “bitch” so much? You can say “contract worker”, “tied to the devil”, there are many other words besides profanity that you can use. I admit that I don't like Jahaira, but I'm not saying that “that old bitch is really pissing me and Astarion off”.
I want to point out that you can specifically ask Astarion if he's bound to Mephistopheles, and he says no. So he's not Mephistopheles' anything. His exact words are, "Mephistopheles has made a new monster, not bound a creature to his will. The rite was honored. The sacrifice is over."
We can certainly debate about the evilness of the ritual, but the game makes it pretty clear that the deal was, "You give me 7k souls, I give you some cool powers." It's a transaction, not an employment contract. He's not bound to do anything for Mephistopheles, now or in the afterlife, in the game's stated canon. DnD canon doesn't always apply to BG3; if there's a contradiction in the game, as far as I'm concerned, my default is to trust the game.
And I agree with Marielle. This is a world where survival is never guaranteed. The more limitations you have on where you can go, what you can do, the less free you are fundamentally. Whether you're willing to screw people over to get more freedom, that's something only the individual can decide. But I don't hold it against Astarion that he rightly recognizes a tadpole-less life as a spawn has limitations that are challenging to overcome, and that he's not willing to become a better person just to deal with them. I've played the AA route the whole way through, and I see absolutely no hint that Astarion isn't free from Cazador. He seems nothing like him to me. The only "hints" are when Tav can say, "You're just like Cazador now," but I struggle to think of any examples that prove this, and honestly, I hear the refrain, "He's just like Cazador" on Insta and YT comments CONSTANTLY, and have yet to see any concrete examples that, as I've said before, boil down to just "vibes."
