Actually did a find on the House Rules page, and the rules for exposure for French are as I remembered. 4 xp per season Exposure, unless you take Exposure in something else that season (e.g. Corpus, Magic Theory, or Teaching), up to a level of 4. Once you hit French: 4, you don't get that exposure anymore.
Just below that is the Advancement rules for statted-out grogs and Companions: 30 xp per year (10 xp per season for three seasons, with one season free), plus any xp you get for adventures. Although JL did say in that post that "specialists will advance much more slowly, based on a formula to be explained below", but I don't remember seeing that laid out yet.