I agree with Dwight instead of facilitating the creation of tabs why not just present the tabs. Most on this board dont agree with playing using tabs but a few of us do. I would be interested if tabs were part of the deal instead of me having to do the work.
You're right that the two books out are not focused on accordion. The sheet music for Ann Savoy's book seems to be for the vocals. The yellow book is from a fiddlers perspective.
Larry Miller did put out a book with several songs and tablature. Can't remember if it had sheet music though.