Critter Compendium module tokens not registering as assets in FGU

[Wargrim Deephelm]

The Critter Compendium module that I purchase on the DM's Guild functions fine in FGC but the tokens don't register as assets in FGU. I'm puzzled?

[Wargrim Deephelm]

I opened the module and the tokens are .tiff files. I could convert them to .png files with an online converter to retain the transparency, but there is a few hundred of them. Anyone aware of a more efficient option?

[LordEntrails]

Gimp and other graphic programs often have batch add-ons that will convert entire folders of images without intervention.