Problem
Lumen is a speed-reading and focus trainer for people who want to improve reading speed without losing comprehension. The product expanded into multilingual use: someone can use the interface in English, Afrikaans, or Portuguese while training in a different language path. That meant the app could not treat "language" as a single setting. It needed separate app-language and training-language state, per-language progress, reading history, spaced repetition cards, analytics, onboarding, and a native payment model across web, iOS, and Android.
Most learning apps bolt translation onto the surface after the product is already built. Lumen needed the opposite: language had to be part of the product model. Progress, cards, reading sessions, comprehension, and coaching only make sense if the app knows which language the learner is training. Once that was true, the interface language could become a separate comfort setting instead of a constraint on the learning path.