If I had to guess, create a new rule.
First line:
^(?:furbooru.org)/(?:images/)?(\d+)[^.]*
Second line:
Third line:
copy/paste the whole thing as is
Forth line:
^furrycdn.org/img/(?:view/)?20\d\d/1?\d/[123]?\d/(\d__)/.__
No idea if that’ll work or not though. But that should be t least a good jumping point.