Maybe I'll need to modify the Readwise export to put Tags and Notes in the same block as the text extract? Edit: Nah I don't think so.
Watch Database (Library) for Updates to get the Page Content (Currently not available, but it is possible)
Get a saved record of the Old Page content
Use Old page content as regex find, and replace it with empty string. Leaves the New content
May have to replace * ? etc with the escaped versions
Get the New content
Then use Regex to extract the Tags/Notes
Then Search Objects with that Tag for a page title
Then update that Page with the text extract (Currently not available, but it is possible)
Or even better, with:
Creating Global BlocksUpdate the Old Page content record