The general process (maybe not always) is:
1.) Determine if the text is in VDP1 or VDP2 Ram. (For yabause use the viewer, for mednafen dump the ram and view in something like crystal tile 2).
2.) Determine a write trigger address for use in an emulator.
For vdp1: dump the command list and determine where the command to draw the text is located.
For vdp2: You probably want the address of the pattern table location that corresponds to the ‘O’ in OK
3.) Set up the appropriate write trigger just before your menu is displayed. If you are lucky it wont be periodically triggering due to other events going on in the preceding screen. Then reenter your menu, and the trigger should activate.
4.) The sh2 function you are in should probably be either at the same level or one or two down from the one responsible for printing the text. Start reverse engineering dynamically here. Alternatively save the state and load it up in ghidra and try there.
5.) Eventually youll find something that gets passed in the address of your text and a length to print. Adjust the length appropriately. Youll need to modify the asm instruction or a constant thats buried somewhere. Also make sure that increasing the source length of your text does not have unintended consequences (pointer tables, overrunning ram etc)