Thank you for the report, i feel as though i should give a explanation of what went wrong i feel as though you put too much time into this not to know.
Basically i'm just an idiot and forgot 1 line of code in the reduce curse spell. basically each limb knows weather or not its transforming, its current species, and its transformation percentage. There is also a global transformation for the enemy which we use to tell if we need to give flavor text, or if you lose.
When a limb reaches 100% transformation progress it stops transforming.
When you cast reduce curse the limbs local percentage and the global percentage both go down. The error was that i forgot to tell the limb to start transforming again. this is a problem because the game thinks that the limb is at 100% transformation when in reality its at 80%. (i should also note that this glitch did come up before. at the time i thought the math for updating the limbs local percentage was wrong, which it was but in hindsight it was probably this glitch the entire time)
because of this the limb never updates its transformation percentage again leaving the global transformation percentage below 100% which is the games lose condition, so invincibility.
The reason why higher priority tf's can break the glitch is because the higher priority tf is expecting to transform limbs that are already fully transformed. so the tf correctly adds itself as a secondary transformation and then tells the limb to start transforming again so the new transformation can take over the old one.
Fully curing the transformation also breaks the glitch because when you fully cure a transformation the limb no longer has a species and its not transforming. aka the limb is just a normal human limb so the code works correctly again in that case.
I should also point out that reduce curse does not slow the the transformations at all. if i had to guess why the transformations are seeming a lot slower then usual is most likely because of the environmental factor. a quick test shows that if your transforming into a cat, full, and in the snowy biome your transformation multiplier is set to 0 meaning you won't naturally transform. even apun death. i might tone it down so your just slowly transforming in the worst case.
The explosive transformations if you were starving or nearly starving is intended. taking your bat as an example at base bats can fully transform you in around 600 turns. the starving penalties are pretty severe. if your fully starving your transformation multiplier is set to 5.5x or 2.5x if your just nearly starving. (ignoring environmental factors). the penalty for death is 250 turns. at a 2.5x we expect you to fully transform into a bat in 240 turns. so most of the time you should fully transform into a bat most of the time upon death even if you weren't previously exposed to it.
As for the the inventory bring broken this was also fixed. apparently i'm just a fan of forgetting code because i forgot to add full inventory check if the item is new.
Yeah the transformation system should be overhauled. but hopefully in the meantime the current system won't break. Honestly if your up for it, a psuodocode example of the new transformation system would be great. as im a bit confused on how you wanted the number to change and just took a guess. even if in a different language the fundamentals should be the same and i should be able to translate it to c#.
Again thank you so much for the feedback. hopefully its fixed for real this time. I hope you have a good day yourself.