According to Jochen Vollerts book, Tyagatshi the Ya-12 went into
production in August of 1943.
I dont think that many would have been captured by the
Germans and even then fewer painted in German colours and even fewer marked with German markings other then a cross to stop fratracide.
As for units that used them it would be ad-hoc use to say the least as replacement parts would be vertualy non existent and extended use would be minimal.
Now saying that, someone will have loads of photos with all the markings including number plates.
As they say "never say never"