I'm not sure if it's something you want to include in the blog post but one of the potential advantages that used to be listed on Wikisource's help page is "No copyrights infringement for the actual phonogram, as no artist actually played or recorded the work." (Now moved to Wikisource:Sheet music.)
I mention this because I recently tried to work on Over There (a WWI song). It apparently used to have an attached recording, which was deleted on Commons because sound recordings are never in the public domain in Florida. When the bugs are solved and Over There is transcribed, Score will be able to fill that gap.