Adding/removing languages has an unclear process

Desktop → Raspberry Pi 5 desktop OS → install en,fr,de.
Q1: how to add more languages?
Q2: how to remove languages?

Phone iOS 18.5 → LiTranslate (by Deep Jerajbhai Davara) → Translate → English → Search: french → select French → added.
Q1: how to remove from Recently Used?
Q2: how to add more languages to All Languages?