Comparatives should be spelled with an f, eg talaf, gwaethaf but the South Walian tendency is not to include them, wheras I am not arguing that this in incorrect, the other form should also be added to the database.
I agree, both should be accepted. Report it.
By the way, it's an informal thing, not a southern thing. Northerners drop f more than southerners e.g. ara', ha', co' etc. as opposed to southern araf, haf, cof. Certain southern dialects use forms like af i, gaf i, wnaf i quite naturally too whereas you'd only get (mi) a' i, ga' i, wna' i in the north.