I think you should concentrate more on finding the desired adjective to describe your “research work” or better yet your “research results” than on finding one to describe your “research topic,” because based on the way you describe your “research topic,” I think it sounds like a “general research topic,” which really doesn’t give the positive spin that I’m sure you are after.
Here’s one way that you could perhaps put a positive spin on having [had] a “general” topic while using either (or both) of your two good suggestions (“multi-purpose and “versatile”) to describe the “results” that you achieved:
“The topic of my research was/is sufficiently general (or “just
general enough”) to permit me to work on multiple applications/issues
and achieve multi-purpose/[and] versatile results.”