[gdw]
Although from an etymological perspective romanz and romance1 are two separate words (from, respectively, roman + us and roman + tia), the almost complete semantic overlap between the two, together with a potential for orthographic confusion, suggests that medieval users probably did not distinguish them.
The unetymological rim/rym- variant spellings may reflect an influence of rimer (‘to rhyme’). However, the evidence of the attestations does not warrant the creation of a separate, and otherwise unattested, *rimance (‘a rhymed composition’) entry.