I agree with others above that the ideal answer is 'both'.
For my own purposes, when I'm working up a song I'd rather do my own editing and emending: comparing with other versions to clarify a line, or re-introducing a verse to make the narrative more coherent, all toward my objective of having a good singable version, while not doing violence to the original.
But I'm overwhelmingly persuaded by the objective of providing an accessible format, so that the songs are discovered and sung by more people. (People who don't have a whole library of other versions to do their own research). So that lots of people will buy the book, and not be put off by too much 'scholarly clutter'. [This from one who fully appreciates, and whose workspace is filled with, 'scholarly clutter.] On balance, I would be happy to see a lightly edited 'accessible' version in the published book, with emendations or insertions clearly marked [in brackets, say], and even including appropriate additional verses sparingly added to incomplete versions. Again: clearly indicated. That said, however, I would want to have (non-cluttery) marginal notes or endnotes documenting any changes.
And I would want the complete (or incomplete) original transcription available in the companion on-line site. Along with some assurance that the on-line site has a permanent home and archive. [A scholarly website, with an auxiliary book?]
I have to say, Julia: I'm very much looking forward to seeing the results of your efforts!!