The LBA accepted my US PPL as proof of language proficiency, however level 4 only and i had to renew as if i got that level 4 on the first day of the language proficiency rules. Since then my company build up their own lLTO and we are checked during our simulator events. The german JAA ATPL received two extra lines on the back for the language "checker" to extend the duration of the level 4/5 proficiency.
By the way, LPLUS is indeed not certified in germany as an LTO, however it is the sole language testing provider in austria and certified in other european states with its online system.