Among the pre-reformation humanists there was a Latin phrase they loved to use: "Ad fontes" (to the sources/fountains)!
The idea is that the intellectual sources were the fountains from which the stream of their thought came, so if you wanted to understand ideas, the best place to go was the fountain from which the river of the idea flows: so, Ad Fontes!
Maybe that'll help someone other than just me to remember the word, if not, maybe it'll just be a fun bit of historical trivia (well... I think it's fun anyway).
Yes, it's an oversight. La fuente / las fuentes is pretty much a direct equivalent of "font" in English; it originally meant only "source" (of water or anything else) and now also means "typeface" (also written in Spanish as "tipo de letra"). If any synonym for those is not accepted, you should report it.