I'm talking with Pat about the customer service issue on another thread, but here's an answer about Premiere Pro language specifically:
Because Premiere Pro isn't localized into Czech, Premiere Pro will run in English in your case.
Of course, you may prefer to have the rest of the software in English, but Premiere Pro should already be as you want it.
While on the subject of languages, my OS and all my programs are English, both CS4 and CS5 and even some CS3 programs. One exception is Adobe Drive CS4. It start in English, but during the splash screen it switches to Dutch and refuses to run in English. Is there any way to disable that behaviour? Notice that my keyboard is set to International English, but my location is set to the Netherlands.
FYI - In addition to Todd's responses, I have been contacted by a SENIOR CUSTOMER SUPPORT CONSULTANT in the NORTH AMERICA CUSTOMER CARE org at Adobe who is managing the this case. I certainly appreciate the efforts the efforts Adobe is making in respone to my forum posts - thank you.