I've tried what you suggest but it doesn't seem to work i.e. I've searched on the Cntrl F 'Find Ladder element' facility using Fn_#76 as an example, where I know Cf#76 exists, and still nothing happens.
I've also tried many variations on the theme but I still have had no luck.
Using the Cf label name works OK, but I believe searching using a Cf number would be far easier to do. Do you have any more ideas?