There’s not much to go on here, as I don’t know what you’ve tried, and what did (or did not) work for you.
I’m going to guess that MIDI Channels aren’t the same for both of the FCB1010 pedals and the H9. The Behringer MIDI Channels all default to Channel 1 (if you haven’t changed anything). If you need to adjust that, it’s under Global Configuration. That process is detailed under section 2.2 in the FCB1010 manual. You need to set each physical controller type individually.
You can also change MIDI Channel on the H9 end to match (easiest in the H9 Control app). Set the H9 Output to THRU. Again, I’m not sure which MIDI CC message each FCB1010 pedal is sending. It’ll be different for each switch position / preset. The default CC for (at least) the left pedal is Volume – CC #7 (I believe). The right one may be CC #11 (Expression).
The easiest way to lock the transmitted CC message to the received CC message is to use the H9 pedal’s LEARN function. And you’re going to have to look up that process in the H9 manual. Good luck with getting this all straightened out.