FZ1000 in the lens data is wrong. It is sufficient to add the true camera model name like this:
<model>DMC-FZ1000 FZ1000 & compatibles</model>
Untill now I never saw something like “lens make” in exif data.
seems so just an information helping to read the file. It should not matter.
I can open a new ticket on lensfun but, lensfun team being small, they cannot be very reactive.
One other possibility is that I correct the DB in my local repository and submit diff files to the lensfun team from time to time.