Surprisingly, the most irritating nitpick for me is the choice of the file extension — surely that should've been ".cu", not ".co"? If I were developing an e.g. Iron programming language (hypothetically — although perhaps so named a language already exists), I'd pick ".fe" in a heartbeat.

Then again, I'm the kind of person who've chosen $'.\U0001F9CC' (that is, $'.\xF0\x9F\xA7\x8C') for a file extension of my own toy language so...