To answer your specific question, I do NOT think there is any "de-compiler" for Micro Focus COBOL (on any platform). There are de-compilers for IBM mainframe COBOL - but that is the only platform/compiler that I know about.
If you have .INT or .IDY files for your Micro Focus object CODE, you *might* be able to reconstruct your original source from that - but I find it pretty doubtful.
As stated by others, the symptoms you report are pretty typical for recompiling the SAME source code- but with different (Micro Focus) compiler options/directives.
Bill Klein