I read a suggestion, I think it was in the PTG forum, years ago, that PVC-E might be the same as Evacon-R bookbinding adhesive https://store.bookbinding.co.uk/store/product/5130/Eva-con-R-Adhesive-500ml/
Some years ago I obtained some Evacon-R. I've never used it for a whole set of keys, just for little jobs here and there around the house - and for sticking some books together!
I stuck a plastic sharp to a little piece of mahogany and it stuck extremely well, even though the surface area of a plastic sharp is small, as they're hollow. I also stuck a plastic white key covering to a little piece of pine. That stuck too, though not as well as the sharp to mahogany - I was able to pull it off (after a week or two) though it would have stayed on had I not pulled. And I had not 'keyed' the surface of the pine by light sanding; it was very smooth.
I also stuck some little bits of felt to the mahogany, and they stuck well. It does take a while for the Evacon-R to dry. The blurb says it can be thickened with a starch paste, which might be worth doing, as it's pretty runny.
It looks and smells like PVA, but it is chemically different. It retails some flexibility, rather than drying brittle. Which, I guess, is what you need for bookbinding.