They are not sealed, at lest they are not top secret.
I’m not sure if I still have it, but I red an article about Schmeisser’s work in USSR, basically he was bored to death, as they only gave him some minor, pretty primitive jobs. I guess the main point, if there was any point at all, wasn’t to get Hugo exploited as much as possible, but to not let him fall in the hand of Western allies.
. Besides, why would Russians admit German involvement in work over early Soviet ballistic missiles, but not small arms?