Thank you Lisa. I just sent of an e-mail to you as I found the address in one of your posts.
Have you considered request a church marriage record? The license never has a place of birth.
No notation Na- on 1930 census? How about a WWll registration form?
A bit unusual him not filing an Alien Registration Form?
Sometimes our ancestors would put down Austria and should Hungary but since your ancestor put down Czechoslovakia than possibly he was from Ruthenia region www.cgsi.org which is now Ukraine.

Why was he adopted?

Beretski could be the Bereg megye that I mentioned in previous post.