Consider extending misspellings checks to Wikisource
Wikisource contains a lot of transcriptions of documents, audio, etc. It would be great to either consider it as a source of misspellings, filtering mechanism for the misspellings, or as a potential end consumer of the copy-edit tool. Either way, at some point it might be interesting to count the instances of potential misspellings in wikisource to guide this choice.
It also has potentially useful templates such as: https://en.wikisource.org/wiki/Template:Sic and https://en.wikisource.org/wiki/Template:SIC