As an out of the box suggestion in case you haven’t found an answer, try this.
*IF you can access the files via SMB/SSH/or directly with keyboard and mouse by going to linux side on the device like the directory here “/saves/psx/(gamename(disk1)).srm” try copying the file and rename it to Disk2 for example “/saves/psx/(gamename(disk2)).srm”. I tried this renaming a game that was miss spelled and it ended up losing my saves till i realized the .srm file name just has to match the game your playing. If you found a better way let me know! Going to be playing FFIX and will run into same issue.