How do I go back to a factory reset , or “recall” for one specific performance, without doing a factory reset for the entire keyboard?

You don’t do it that way.  You LOAD the PERFORMANCE desired from a backup File.

Do you have a “Factory Condition” backup file? (Highly recommended to make one of these prior to overwriting any PERFORMANCES, for precisely this purpose)

If you don’t have the file referred to above:

SAVE an ALL file of your current setup to USB
Perform a Factory Set
SAVE an ALL file of the Factory Set condition
LOAD your All file SAVED in step 1
LOAD the desired PERFORMANCE from the Factory Set ALL file to your machine.

Be sure to keep the pristine Factory file somewhere safe for future use!

or possibly use the backup file from someone else you know that has a moxf or someone on this forum that has an original backup file, and then restore the performance you need that way.

Moxf files are compatible with other Moxf files, another Moxf user could e-mail you the file :-)