For the record, we do only have the regular gnome faces, but let’s be honest, you don’t roll a mechagnome for the face. You roll it for the mecha part. For instance:
Sure, the ears and the eye mask can be customized separately (so you can have the eye mask with any set of ear modification, or even mechanical ears with just regular eyes, or one of the eye masks with regular ears.
But if you roll a mechagnome, but don’t have the mechanical eyemask, why are you rolling a mechagnome?