That doesn't work here because the data was not wiped by a generic cache flush from a third party script or whatever, but a targeted hit from the application itself on files known to be persistent undo.

You just can't point the finger at file system standards, or shoulda-read-release notes or whatever.

There is no such thing as "by mistake, we historically stored persistent files in a directory with 'cache' in its name, contrary to a popular standard, so that makes it okay to trash them now".