Whoa, that's a big review. Thanks for taking the time to play through the game and tap up all your thoughts like this.
As the writer for the game I can answer some of these things. I can tell you that Chief Maku absolutely had his personal reasons for choosing Kivuli to be next in line, reasons that may become more apparent as the story progresses.
I can also tell you that there's a bit more explanation to Kivuli and Sumari's relationship if you take the time to 'accidentally' walk into all three of the net traps during the prologue.
Finally I can say that I did have the desire to add some conditional dialogue to the NPCs regarding Kivuli's status, but the amount of background programming it would take for just small pieces of dialogue, and that I'd have to make said dialogue both flavourful but not get in the way of character relationships and important instructions, it just ended up being way more work for the comparatively minimal gain from it.