Combine multiple traces across different .r files to reconstruct the system's behavior.
Instead of decompiling the .r file, run the program in a debug environment with SESSION:LOG-MANAGER enabled. Capture the ProcedureLibraryLoad , Run statements, and database accesses. This gives you a behavior log, not source code, but builds a functional spec.
: Decompiling applications for which you are not the lawful copyright holder is strictly prohibited and may violate licensing agreements. Code Fidelity
Or for a saved .rda / .RData with a serialized function, try: