Polyglot

Needs Royal Court. The wiki build: a 21-year-old custom character with the Erudite Oracle trait and spare points into Learning, from a culture with Astute Diplomats (+1 language limit, +25% Learn Language scheme power - Franconian, German, Nubian, Croatian and friends) or Culture Blending (+30% power, +1 concurrent scheme - Mon, Avar, Merya and co). Take Pedagogy and Open-Minded with the free perks, then cycle Learn Language schemes back to back; the Diplomacy lifestyle's Adaptive Traditions perk adds another concurrent slot. Sneaky shortcut: converting or hybridising into a culture with a different language teaches you it instantly - which is Converging Paths anyway.