I am not sure the internal format of XLSM and how the macros are represented within it, but I would assume they are stored in the form of their source code as a

I am not sure the internal format of XLSM and how the macros are represented within it, but I would assume they are stored in the form of their source code as a plain text file within the ZIP archive that is the XLSM file and if that's the case, my tool would work with them just fine.