Leaderboard

Option (1) completely override the loot table by creating your own and putting it in the same resource directory as the vanilla file (e.g src/resources/data/minecraft/loot_tables). This is a last-mod-wins solution. Option (2) append the loot table using the LootTableLoadEvent. By appending you don't interfere with other mods, but also can't prevent existing drops (so you'd get bones AND your item instead of bone OR your item). Option (3) use a Global Loot Modifier. This is by far the most flexible and powerful option.

Can you be more specific? Maybe a screenshot? Not totaly sure what you mean, and I haven't heard of anything described like that.

For the action bar message, you can just use ServerPlayerEntity#sendStatusMessage with the second parameter being true to send an action bar message to a player. For the Totem of Undying animation, you have to create your own server-to-client packet which has the line Minecraft.getInstance().gameRenderer.displayItemActivation(...)

Did you install the same version of Forge to the client as you used when making your mod? The error log is referencing Food.Builder.effect(Supplier,float). That method was changed in Forge build 1.15.2-31.1.5, which might be what's causing conflict if you're using different versions.

Because at this point there is so many things that can go wrong, and it would take ages for other people to guess one by one. By seeing your code we can stop guessing in the dark and instead figure out what is wrong immediately. An analogy that is popular on this forum: just like in real life doctors have to examine your body to figure out what is wrong; they can’t magically know what is wrong if all information they have is “doctor it hurts”.

Reflection would allow you to make it not private so you could create a new entry. I can't seem to find the tutorial on reflection but this is one on access transformers which also links to some useful tools and examples that will help you. https://tutorials.darkhax.net/tutorials/access_transformers/

1.8 is not supported here. Update. Also: Don't do this.