All I could find after reading several (Metz 44/48/50 AF) manuals and searching the net was that a FZ only will work manually with a slave flash. You'll need a flash on top of the camera which has to be in manual mode to trigger a (optical) slave flash. This all has to do with the pre-flash of the FZ camera's, which you can't turn off, triggering the slave to early. This is at least my understanding after forementioned research.
After writing the above reply I checked the Metz AF-52 manual and found this,
so it looks like a Metz 52AF will/might work with the (even in camera?) flash:
Signed, Jacob O
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