Okay, you may need to define "files". "Files" as in banks of presets that replace the factory presets, or "files" as in sequences? Huge difference there. I still have a Yamaha FB-01 module from the 80s that would accept custom designed sounds via sysex, but it had no sequencer. The banks of sounds are "files" too. I suspect you have something similar going on here.

Nothing says that you can't PLAY those sequences from another storage and playback device. That would come down to the capability of your synthesizer, i.e. how many voices is it. If it's an 8 voice, you are splitting those 8 voices between different instruments playing back on your tracks.

Again deferring to those more schooled on Yamaha, is his model higher end or lower end? If it has no sequencer, I assume it's the latter, particularly knowing how long ago onboard sequencers became the standard issue.

I am using the new 1040XTRAEZ form this year. It has just 2 lines.

1. How much did you make in 2023?
2. Send it to us.