Absolutely failing the skill rolls, though, would cause a player character to not advance a year/level up. That's not great in real life and not fun in a game, so I'd want the chance of that happening to be very low and something players could resolve with "extra credit" adventuring.
Consequences in a school-like environment are a tricky thing. If there's an in-game benefit to studying hard, then a significant amount of PCs are going to study hard. The real-life motivation for NOT studying hard is 'this is boring!', and of course PCs don't get bored unless their players decide they do. Similarly, the real-life consequences for not studying hard are 'my parents yell at me' or 'i get detention' which as far as punishments go don't really have game-mechanical teeth either.
I'd suggest leaning into the Inspiration mechanics really hard for a game like this. Throw inspiration points around like candy if PCs who have less than studious concepts or flaws etc skive off on a regular basis.
Or possibly have some sort of parallel system where PCs could level up but not necessarily pass exams. It's quite easy to imagine how a bard, for instance, could level up their bardic abilities by being a social butterfly or acting as the class clown/prankster without actually learning much of what they were put in school to learn. Maybe the in-game penalty they could suffer if they DO fail everything is that they have to come in for summer school to do make-up work, and miss some opportunities for summer downtime activities as a result. Schools mostly don't LIKE leaving students back after all, and it makes for a very difficult game experience if your PCs have a party split enforced on them for a huge chunk of game time.
Strixhaven the MTG set had some amazing implied lore. There were super cutthroat interactions between students who would have violent duels with one another or sabotage another student in order to get ahead or claim a discovery etc. The instructors were powerful mages who sometimes had to eliminate students that'd become hostile and dangerous to the entire school. These instructors would also leads student expeditions to different parts of the wider setting, and these expeditions were dangerous. Death was a known possibility for everyone who attended Strixhaven because studying magic, truly studying it, was a very dangerous affair.
This book has none of that flavor at all. Maybe they were afraid due to school shootings in America. As a professor and as someone who was involved in a shooting on campus, I think a mature note at the beginning of the book would have made this a fine theme to keep. It really does not feel at all like the stylish, somewhat-sexy, very artistic, and cutthroat Strixhaven the MtG set depicted. It feels like a PG-rated adventure book that is poorly supported.
WotC should have looked at games like Monster Hearts if they wanted to make Strixhaven a book about the mundane aspects of student life. There are many mechanics that could have been taken from Monster Hearts to help support the ideas in this version of Strixhaven, specifically Relationships. Instead, WotC as usual just didn't have any good mechanical ideas and tbh this book, like most (not all) of their books, leaves me feeling like they just don't know what they're doing.
They really completely changed the tone and idea of Strixhaven and the replacement was a child's version. I know a lot of D&D is for kids, but it's just so mid that they took this cool Arcane University that felt different from others (but relatable still) and completely transformed everything about it into the complete opposite. If you were interested in Strixhaven because of MtG, this book is not for you.