Thank you Lars! Two brief replies:
1. Thanks to you and Birgitte for the clarification about Wikidata. It's looks like that isn't the place to go, but on the other hand what has been suggested here about Mediawiki supporting TEI in the future could open a lot of doors. I would really like to know where to go and who is involved in that.
I personally think that simple scanning and proofreading is the activity where we can most easily grow Wikisource. Since the job is mostly non-intellectual, many people can be instructed to help, without creating edit wars... Translation or scholarly editing requires more coordination and takes more time for a larger work than the sum of the parts.
2. It's important to emphasize that what I was writing about wasn't something theoretical, but something that has already been happening for years at Hebrew Wikisource. We have been doing both critical editions and scholarly editing, have had much fruitful discussion and collaboration, and never even once has there ever been an edit war. Work on projects like these is indeed slower than the process of scanning and proofreading, but the final product is often a much more valuable contribution to the public. (The public domain scan was already available anyway. But where once a reliable edition was copyrighted and unavailable, now an even better edition is available online under a free license!)
I would suggested learning from our experience, and looking at your own Wikisource with a generous eye that values many different types of collaboration on texts towards building a useful free library for the public. While you and others are proofreading, be appreciative at the same time towards others who are editing in other ways.
Dovi