So a German priest, who speaks...German...converts some goat roper who speaks Arabic or Farsi, or whatever? Sure!
My understanding is that the churches in Germany and the neighboring countries had a lot of interpreters and translators to solve the problem, a lot of the Bibles, hymns and other tracts were translated into the local languages. Also a lot of the educated Syrians speak French (the refugees who make it to Europe need to have a lot of money and education to get that far I guess) and many of the pastors also speak French, and the Syrians who get permits are required to take intensive German classes early on. Some speak English and Italian too, so communication isn’t that hard.