Here an update (including source for the github) that allows custom naming of folders. Also as a quality of life upgrade, the currently active folder is selected on startup.
The custom names can be defined in 3DSBank/3DSBank.ini like so:
[3DSBANK]
SLOT_NAME_0 = Favorites
SLOT_NAME_1 = More Fav...
I could claw back 14tb by only doing 2 parity disks but I feel like with 13 disks in the RAID I'd be kind of pushing my luck on rebuild time if I encounter a disk failure