Thanks for giving this some close thought!
While it's not explicitly stated in the text, death spiral mechanics are actually a core idea I wanted to explore here. I think they fit well, at least thematically, for the Rejection system, but agree they may be a bit too broadly applied outside of that. Maybe removing the Exhaustion spiral and replacing some of the complication/advantage table results with more neutral options would help.
I def agree the Flaw and Perk accumulation rate is likely too fast for campaign play; there should probably be more rules around how often you can select them and which types you can select. Space constraints may make pacing those out better tricky tho, we'll see.
Also, point of clarification: as-written, Organ Flaws and Perks notably apply regardless of form - the idea is the transformation you are undergoing as part of a Beast is affecting yourself even as a Human. So you have access to both types of Flaws for Snapping. It's a fair point that the system gives little incentive to pick Organ Flaws tho, that could use some tuning.