Would be cool to have a config option where you can define a custom ID of a dimension and then a string which represents the dimension name that is shown in the rich presence.

This should already be possible, checkout the DiscordRP config

Hmm maybe I messed up the format then.
How do you write it?
Let's take compact machines as an example. Their dimension ID is 144. Do I write that?

144|In a compact machine

I currently have it like that:

but it doesn't work. This shows up then:

Could be I broke something will check it out in a bit for you