ok, one suggestion to save time, try this:
initialise,
load your composer style. Let's assume it is in panel memory 1.
switch on MSA get your new registration, save it in an unused panel memory, let's say panel memory 8, it can be in bank 10 if you are saving only 3 banks if you like.
press panel memory 1,
go to panel memory expand filter, and switch rhythm to OFF, tempo to OFF, accomp & bass to OFF.
press panel memory 8 to get the new registration - the rhythm, tempo and accomp balances of your composer rhythm will not have changed. Now re-save panel memory 1, and save to SD or disk.
If you initialise again and load your panel memories to test the method you will have your original composer rhythm with all its original balances and tempo but with all the right hand registration settings from the MSA that you like when you press panel memory 1. Modify the method to keep any other parameters in the filter you want to keep in your original registration eg pad bank, split point etc etc.