VE doesn't work with ProofreadPage, and the outstanding bugs are not being worked on. There are a few that are impacting normal operation (e.g. T183950) that will be far easier to fix if we're not trying to keep things working for VE.
The consensus amongst the Wikisource developers at the triage meeting today was that we should remove VE support for the time being, and reintroduce it (probably behind a feature flag) at a future time when there more people keen to work on it.