I like that video & his guitar!
I've to wait months for my 11 string but I have an 8 string & briefly experimented with a Baroque lute.
The general advice is, as you probably know, to avoid looking at the RH. This works for me with the 8 string (I can hear when I've played the wrong string) but I can't remember if it was an issue with the Baroque lute.
However lutenists do not spend all their time looking at their RH so clearly a good ear, loads of practice, knowing what the piece sounds like (& bass of the pieces especially) & finally, kinetic / muscle memory play their part in helping accurate playing / finding of the strings.
And what of harpists? They have loads more strings & read while playing so they too must develop these skills & rely less & less on looking at their hands as they get to know a piece.
But if it helps, particularly in the early stages of learning a piece - it might be worthwhile initially to look sometimes at the RH while learning a phrase at a time by heart & eventually try to look elsewhere when you know the piece well enough?
Tell us how you get on either way - I'm interested!