`setTermForLanguage` implies a `Term` object.

This gets more and more confusing the longer we are working on this. Plural words like "aliases" and "descriptions" are an other example. Sometimes "descriptions" means an array of strings, sometimes an array of `Term` objects, sometimes a `TermList` object and it could even mean an array of `Description` objects (which we don't have any more).

See https://bugzilla.wikimedia.org/show_bug.cgi?id=64873