I’d use [name_m]Fabian[/name_m] in a non-francophone country and [name_m]Fabien[/name_m] in a francophone country.
[name_f][/name_f]However I’d probably not use the name in an [name_f]English[/name_f] speaking country as I’d prefer it pronounced FA bee an or fa bee AN depending on country, not FAY bee an;
[name_f][/name_f]I’d pronounce [name_m]Fabien[/name_m] as [fah beh in ]