Huge progress on both figuring out Usermenu as well as the TFOV menu. Given that there were no instructions in any of the usermenu version. I decided to just take a look at all the files itself under a text editor.
I came across a few batch files found in an older version of usermenu called GAL158 (GAL probably means Galileo

). They had a weird format so to investigate deeper I went into Usermenu itself. After firing up Usermenu and hitting F1, I found an interesting function under the Direct Menu Manipulation Commands:
;mn, ‹filename>, ‹menuname> (diagnostic user only).
After comparing this structure to the batch files I found that the command:
;mn,Galuprc,MainMenucame up a alot. So when firing up Usermenu.exe from Menu3 in DosBox I typed in (exactly as seen):
;mn,Galprc,MainMenuAnd boom it showed the advanced menu. I chose this specific command because of what @Fraser found earlier in Galprc
Also notice the difference between the titles in the attached photos. One says
Usermenu Menu: Radiance HS and the other says
Diagnostic Menu: Radiance HS Once I get this connected to a serial monitor I will see what kind of commands (most likely hex) are being sent out. And hopefully this will once and for all solve the mysterious TFOV commands

But it is pretty late so I will investigate tomorrow haha.