Wow that sounds like a really frustrating and demotivating experience. Seems totally ridiculous and beyond any realistic expectations - I’m surprised nobody involved didn’t raise concerns.

I had a similar but not as bad experience. The lecturer was brand new and wanted us to design a programming language after a single vague PowerPoint and the worst introduction to yacc or lex or whatever they are. We were also undergraduates.

After several weeks of complaints he provided an example language and parser etc. Still it was simply too hard and in the end nobody could do it. I believe I managed to add a minor feature to his example language as my submission. I managed to get a reasonably high grade simply because I freely admitted I struggled with the entire task but could explain language theory and made comparisons with other languages I know and what features I would have added if I could.

Some people totally wrote that whole module off and planned around the scoring system where one failed module in a year would just be discounted and an averaged score created.