Exophonic

The role of German as medium for exophonic writers has actually been growing strongly in recent years.

The adopted language is typically acquired as an adult; exophonic writers are not bilingual in the sense that they grew up speaking two languages, and indeed do not necessarily achieve the type of spoken fluency associated with the term "bilingualism."

He became a temporary exophonic writer, composing the part of his first novel in a language other than his mother tongue, […]