Welcome to the PSR Tutorial Forum, Chris!
Please note that changing the icon also will change the name of the file in question, as the so-called "Icon ID", consisting of a period followed by a letter (S or T) and three digits, is part of the file name. If you subsequently change the icon for files (e.g. user styles) used in registrations, the registrations in question will no longer work because they can no longer find the linked files due to the changed file names (just as if you would move the user files to a different location). The Icon ID in the file names (e.g. ".S123") as well as the file extension (e.g. ".sty") is only visible on the computer, but not directly on the keyboard.
By the way, you can rename or move Registration Bank files or change their icon at any time afterwards (except on newer models if the registrations in question are used in PLAYLISTS).
Best regards,
Chris