"German is an important language."
Translation:Is teanga thábhachtach í an Ghearmáinis.
I thought that Haitian Creole might be a possibility, since criól is a masculine noun, but the NEID shows that Háítis is used rather than something like Criól Háítise. (The original meaning of béarla, another masculine noun, is “language, speech” [i.e. the ability to speak, not an oration]; I don’t know if a form like Sasanais was once used but became replaced by Saicsbhéarla [“Saxon speech”, which was still listed in Dinneen’s dictionary], then just Béarla.)
Esperanto seems to take the same form in Irish, despite the ambiguity of whether the R should be broad or slender. I haven’t found a use of the word that would distinguish whether Esperanto is feminine or masculine; it isn’t found in any of the dictionaries. (Sprantais seems to be a more nativized version, and it’s probably feminine. Esperanto seems to be analogous to euro, for which a more nativized version eoró also exists.)
Even O’Brien’s 1768 An Irish-English Dictionary gave its Irish title as Focalóir Gaoidhilge-Sax-Bhéarla, so if a form like Sasanais were ever used, it would have been centuries ago.
EDIT: eDIL doesn’t seem to have a form like sasanais, but it does list ainglis (an Old English loan word).