sure, you need to adapt that information to a Chrome, but it basically works the same. You need to search for the Chromium profile folder and adapt the uri to chrome extensions, but it should be doable
I just downgraded with a backup from yesterday. You need to disable auto updates of the enpass extension for that.
And so I figured out, you can simply download the old version from enpass.io: https://dl.enpass.io/stable/extensions/firefox/versions/v6.6.2-9/enpass-firefox-6.6.2.xpi
You need to put that file with the following name in the firefox profile folder:
Profiles/xxxx.default-release/extensions/firefox-enpass@enpass.io.xpi <= xxxx is some other random name
On macos with Firefox you find that folder here: /Users/<username>/Library/Application Support/Firefox/Profiles/