I would like to see the persimmon tree.

I disagree that it's only suitable for an evil playthrough. There are plenty of special dialogues if you specifically try to resist it.

As far as I understand, to make the playthrough as harmless as possible, you need to save-load scum at every dice roll, and even then, there will be evil moments that are unavoidable no matter how hard you try. But still, kudos to them for at least trying.

I remember people, including many acquaintances, praising the second act as a super-duper cool plot with an amazing antagonist... well, I don't think I need to describe how nonsensical the characters of Ketheric and his family turned out to be.

Well, the nonsensical family is perceived more or less as separate side-quest characters. But Ketheric himself is nothing special, as is the whole trio in general. I think that the cure for the parasite could have been made more grounded and focused on fighting the illithids, because they are strong enough as bosses without all this nonsense with pseudo-religion, controlling the main brain with three idiots, and so on.
I liked the second act not so much for the "main plot" as for the side elements. The aforementioned Thorms, as a separate phenomenon (that is, if you perceive them as people who have adapted after a terrible curse), the dark forest with the prevailing gloom everywhere, where without a source of light you will simply die, the githyanki location, with their children hatching from eggs. Outside the main plot, as separate details, all this looks pretty good.