Welcome to our community, solutionm
If you are using RoboHelp HTML for your project, there really
isn't an easy way to specify you want .HTML as opposed to .HTM.
Sure, you can rename files until you are blue in the face, but it's
going to be a long and painful process fraught with pitfalls.
I'm curious as to how help is breaking. You say that their
application is interpreting your help as application code? Surely
the help lives in its own folder. You might inquire as to whether
there is a way to have their application ignore that folder in the
process. I'm further guessing that your help isn't being delivered
via a browser and maybe is being presented within some window of
their Java application. I think I'd be asking some rather serious
questions of the developers.
Cheers... Rick