You actually needed to be ‘very good’ at math to fluently calculate with Roman numbers. However, I can’t make sense of your examples.

Yes, since Bookworm, there is also non-free-firmware which before was located in non-free. I’ve skipped that for simplicity, as both follow the same rules and non-free-firmware was introduced basically for convenience.

Do you know if either of the non-free repos contain binary files without having the source available?