@ jobble try going to your old XBMC folder in the roaming folder and copy all the rombrowser folders over to the Kodi folders. I had to do this myself all your stuff should reappear as it did for me.
Asrock Rog Z390-H | Intel i9 9900K | Windows 10 Pro x64 | Pop!_OS 20.10 |Nvidia Shield TV Pro (2019)
EVGA Hybrid FTW GTX 1070 | Corsair 16GB DDR4
Samsung 500GB SSD | 500GB Nvme SSD |500GB WD Black Nvme SSD |6TB HDD