Glad to hear you again in Espana. During long holidays, I bought and practiced a copy of Mel Bay's "Carccasi in Tabulature" fingered by Ben Bolt. All are basic etudes. I started CG again a year ago after a 6-year blank. I think I became able to play so-so, in other words, playing loud but inaccurately. Though I had made most of these etudes in my youth, it is worthwhile following them to check how far I go ahead. Besides, Julio Regondi's edtude #1 in C major and a couple of Pettoletti's variations are under finalizing.
You are challenging a tougher piece, Mertz's Capriccio, aren't you? Is this in a series of "Bardenklänge" op.13? If so, what sheet of music, you follow?
Oh, you are great. For me Bach is out of hands as of now.
Have a nice day