Have you read the information above?

• Yes

Provide your logs.

Nothing useful in logs.

Describe your issue.

Unable to use sound events from other mods or resource packs. It doesn't even let you type in an event id the not from minecraft. And when you try change it manually from the config files, it keeps saying stuff like "unable to load sound event", and adding "minecraft:" to the start of it.

Not all sound events start with minecraft: - the minecraft: thing is called a "namespace" - you will need to see what namespace the resource pack sound events are registered under. eg: myresourcepack: means sounds are registered via /assets/myresourcepack/sounds.json

Mind showing me the resource pack you've installed and want to use sounds from?

Closing, no further information provided.

Example pack.zip
chat.json
The original reporter stopped communication, but this is still an issue and shouldn't be considered invalid because as far as I experienced, most other mods/resourcepacks/datapacks can interact with sounds added by each other.

Attached are an example resourcepack and the edited config file from config/sounds that add the sound event "minecraft:sounds.chat_type" to the game, which is a duplicate of the default sound event used that I created to prevent it from creating the noteblock subtitle. The sound event is valid because it can be called by /playsound, but it is not picked up by the mod.

The two issues as stated by OP are:
-a): Custom Sound events cannot be set through the mod menu config, it only lists and accepts vanilla sound events
and
-b) When overwritten to be accepted through the config file directly, it simply displays the onscreen error that it could not play the sound and to check if the ID is valid(Which it obviously is when the game registers it).

Thanks! I'll take a further look when I can 👍

I believe this may be fixed when we migrated to a normal resource pack instead of one being loaded from the configuration folder. Let me know if this is still an issue.

This is still an issue with seemingly no visible change to its behavior.

I need logs, please upload your logs to https://mclo.gs/

The Logs on a completely fresh instance except for Sounds and its dependencies. No resource packs except the example, nothing: https://mclo.gs/TWvlBVd

As OP stated, there is nothing about the error in the logs. The previously provided files are far more relevant to it. There is nothing more that I can possibly provide, except possibly recording video proof that the stated information is accurate.

This actually looks like a vanilla limitation, custom sound events are not registered to the registry, i'll have to look further into this when I have more time.

This will be fixed in 2.5.0