Hi!
This project sounds like a good idea, but I don't really understand how it would work as a tool. There's no API for retracted journal articles. It seems like the best way to handle it would be when you find out about a retracted journal article to just search Wikipedia for the title of the article. What would a tool for this look like and how would it be more efficient that just searching?
I think maybe DOI (https://en.wikipedia.org/wiki/Digital_object_identifier) might be useful there, as many article references are referred by DOI (as an identifyable template parameter) and it may be more precise indicator than just name. Not sure which way is the best to search for it though.