Incase of web application, it doesn’t matter which is the language, because at the end everything is HTML. Incase of desktop, if it is a Microsoft technology, again there should not be any problem. I am not sure about desktop applications developed using non-microsoft technologies. Even if it doesn’t work, you always have option of “click image” … So according to me it shouldn’t matter in which language the application is developed.
This is true only for GUI based applications, but I cannot comment on character based (DOS) applications.