The Learning Tools Add-in for OneNote has made language support for Immersive Reader an optional feature, as described in this article. IT professionals who deploy the Learning Tools Add-in for OneNote in their organization using LearningTools.msi will now need additional packages to add support for non-English languages. These additional languages add support for the Immersive Reader Syllables and Parts of Speech (Nouns, Verbs, and Adjectives) features, enabling those functions in Immersive Reader for OneNote pages that contain these languages.
Language packs for the Learning Tools Add-in can be found at the Microsoft Download Center. The Microsoft Download page contains the current list of language packs available for the Learning Tools Add-in. New languages are being added regularly. As new language become available, they will be listed at this Microsoft Download Center location.
You may install as many language packs as necessary. If no additional language packs are installed, the latest versions of the Learning Tools Add-in for OneNote will only support Syllables and Parts of Speech in English.
Language packs are installed per-machine for all users on the machine, just like the Learning Tools Add-in.