How to translate foreign-language theses into English?
If you have access to the digital copies, then dump the entire thing into Google translate so you can skim read it. Having done that, it would be a good idea to find a native speaker and get them to check the translation of specific sections that seem relevant on the basis of the automated translations. I wouldn't suggest asking a native speaker to translate the whole thing, or even read the automatically generated translation of the entire thing.

Another thing you could do is see if you can find other papers that cite the papers that you're looking at. One of them may contain a summary that'll tell you if you need to bother pursuing that particular paper. This will be pot luck though, and it will be a lot easier to just use Google translate.

Of course, don't use Google's translations in your work; get a native speaker to help you when it comes to that.