Would it be possible to change the square notes into the actual notes?

 

Or I'd say create an inlay that has the letter notes, maybe at least whole notes, but that changes with the tuning.

 

Might help subconsciously learn the notes, mostly I can only *hear* a couple chords, like G, E, and maybe D, and A. Chords are displayed prominently. As for individual notes, I can probably tell an open A without thinking, other than that I don't think I have the aural vocabulary. 

If I had to guess, changing the note blocks to letters is just not possible.  Even if someone knows how to replace the textures or models used, I doubt the game tracks what the actual note value is when it renders the blocks.  This would almost certainly need to be a new feature added by the developers in the next version (fingers crossed).

 

There definitely are custom inlays people have made though.  This site has the templates to create custom inlays, including some with notes on them, as well as tutorials on how to generate the dlc package and install it.  The tutorial thread here looks to have an alternate method as well as a bunch of custom inlays.