Why isn't hoffi used here?
licio and hoffi are synonymous. Both are common, so it's important to know both.
Licio? Is that slang?
No, it is widely used alongside hoffi all over Wales. It is a bit newer to the language than hoffi, though, having been in use for only 400 years or so...
I used hoffi and was marked wrong!
If you say what type of question it was and exactly what your complete answer was, somebody may be able to say what the problem was.
hoffi is in several of the accepted translations here.