Hello! The initial stat glitch happened in about week 4 in my first playthrough, and in the second it somehow happened before the first meeting with the council. (I remember bc the council commented on it, and that's when I noticed the huge jump in Endurance points)
The black screen glitch was around chapter 9 I believe (when the MC ends up in the infirmary) and bc I spent so long trying to fix this one I know the next scene was supposed to be Arien mind blasting the boys bullying the MC. In Grey's route I never got to continue past the black screen, but I believe it was around week 7? I had definitely chosen him as the LI and had already done the hang out in the Autumn courtyard after the threatening note. These glitches are unique to this version, I played through Arien and Kai's route with no issues in the original. If I can help more, please let me know!