Often the Manual Resolve fails but I can easily find the meta data for a source online. I find this happens a lot for conference papers/proceedings.
It would be nice if you could import the meta data for a source from a bibtex entry or URL found online, like from Google Scholar. I.e copy and past the bibtex entry and ReadCube processes it into the correct meta data fields. In a perfect world, the program would then retry the resolving process with the added meta data.