From my understanding the fishing journal should update once you catch a new fish, but it hasn't been doing that and the reasons why elude me.
Mod Loader: Fabric
Game Version: 1.20.1
Mod Version: 1.3.4

yeah, the interface is bad.

ignore the "check back here later" message that covers the whole screen. and click a small button in the right corner.

Oh I did NOT see that okay thank you, you saved my life

Yeah, maybe I should improve the interface lol. Sorry!