Why are you doing it in such a complicated way?
Minecraft already has support for synchronising simple data for a container menu to the client.
Look at how the Lectern uses the LecternBlockEntity.dataAccess and LecternBlockMenu.lecternData
to synchronise which page of the book is being viewed.
Or look at how the furnace block synchronises the progress bar (it's similar).
Looks like one of your mods has not registered its sounds properly?
The error message you show doesn't say which mod or what sound.
Maybe your debug.log will have more information?