Glad to see you're making progress in understanding the firmware. I think you are right and I shouldn't make more assumptions until we have a real case where we need to change file lengths or names.
I am trying hard to find time to read the Fujitsu documentation before diving in the code. It's been a long time since I last wrote assembly code (ahem, on a Z80 :-/) and complexity had nothing in common with a camera firmware, so I know it will be slow and tough... but fun
You really deserve the full credit for this project, Simeon, and it's always a pleasure to read you.
Have a nice day,
Vicne