15. Send the companion to the dying Mind Flayer and let him eat the companion's brains, while the rest of the party should be far away.
After a visit to the goblin camp, there should be no scene with a dead mind flayer, plus this mind flayer should break the plot if he remains alive ... but Larian 100% did not implement this if he cannot even be cured in the usual way.
16. Everything related to Kagha is already described in a separate topic, now her quest is strange and incomplete, but I hope these are just problems of early access
17. A player who knows the spoilers can try to save the life of the goblin Sazza. Free her from the cage, take her to the entrance to the Grove, but do not take her out completely. Divide the group, and go to Minthara as the main character, take the quest to destroy the Grove. Or destroy all the goblin leaders with a party of 3 people (Sazza afk). I have not tested it, but I am sure that the game does not give a reaction to this. I think 99.9% of all players who do this know spoilers, so you need a voice of a narrator, an Easter egg, whatever.
If you do that, then keep Sazza alive until the end of the Battle of the Grove. I think it deserves an achievement, an opportunity to choose Sazza for a one night romance, and comments from companions and others that we are strange and disgusting. This is if the player was on the side of the tifflings.
Minthara should try to kill us immediately when she finds out for whom we refused to sleep with her.