Reason: This would allow server to serialize better display info into packets and send to the clients appropriately if the server has custom advancements.

In my opinion this would be something you might want to use a mod like Triumph for.

but if the json for better display is in the custom advancements on the dedicated server, the information simply cannot be sent to the client properly.

I am aware of that, but the syncing of advancements is out side of the scope of this project. I would prefer to keep this mod client side only. Also in my opinion, I don't know how large the user base is that creates custom advancements in the default minecraft format with the better advancements better display info.