That sounds good to me
And while I do not explicitly state it there, deep-seated illness can be reverted to temporary illness with additional Love/Lust bursts.
You should add that note to the feature list
I generally play with only 1 major power + the starting enhanced senses so Sympathetic Link is unavailable to me after I have selected Psychoism, thus only Insanity Aura can remove it. It is more fitting that the power that is all about sanity controls it.
Since I never use Feast of Fear I added a removal of broken and obsessive/nympho to the effects of the power, ideally if all auras were collapsed into one ability a power would be added to remove those states. That doesn't fit with the goal of your mod of course.
As for ideas that might fit:
char_regen_loop in func_time.rpy controls NPC willpower gain, I add a check to the +10 willpower to only happen if the characters are not broken. Might fit in with your view that broken exists to make giving conditions [and maintaining them] easier.
Starting with flaws. I usually just add incest or whatever via console commands so I don't need to get a specific power to have them, and remove Anililagnia if I choose Flight.
Provided you implemented the previous idea, the Mother is decidedly a Milf but does not require Anililagnia to find her attractive. Adding the Anililagnia requirement scenes is a huge pain in the ass but is nice if you only find the sister attractive like myself. Probably would be too much work for such a niche benefit.
The ability to use powers on Sophie while she is asleep would be excellent, she is a massive grind otherwise. I add options to the menu after "Get a closer look at her."
Thanks for all the hard work on the mod, we appreciate it