I have a 'fuge above my sump and I get this sometimes (new sump planned - no divorced 'fuge)
In my case it's air being sucked into the standpipe
The vortec is pretty strong, even at only a couple hundred gph, and creates noises/bubbles. Clicking, thumping what have you
It's very sensitive to the level in my sump and as was stated in your case, your temp sump is probably the cause
The only way I can get rid of the gurgling/clicking/etc is to plug the standpipe with the bulb of my turkey baster until the 'fuge is quite full. The extra water height flushes all the air out and it's done - 'till I mess with a pump again and upset the sump levels
Using the bulb allows the flush without messing with the gate valve
With that said ... maybe you can still fix it with the temp sump in place
What's the water level above your main standpipe ?
Not that there's a magic #, but I'd be looking in the overflow box to see there's not a vortec happening there