Hi all,
Some tools exists outside Wikisource, for instance I know https://www.textrazor.com/demo who find the Qid of words in a text (very good quality but proprietary) or https://ordia.toolforge.org/text-to-lexemes (crude but open, based on SPARQL and for Lexemes), that can generate annotation on the fly. It's not easy (there is a lot of questions) but I'm confident that some things are doable (at least as a POC).
Cheers, ~nicolas