Tried to use a Wunderreich imprinted whisper on a villager and the trades just kept rerolling randomly. The wunderreichAllowLibrarianSelection gamerule is true, config has not been altered, and the only mods present are Architectury, Cloth Config, Fabric API, Mod Menu, REI, and Wunderreich.

Thank you for reporting. This is fixed in 1.0.8.

Thanks!