Client: Forge and Journeymap.
Server: Forge and Lost Cities.

When lost cities is only on the server, and you sleep in the bed it does not 'teleport' you to dim 111. It converts the land around you. Same thing if you are in the lost cities dimension and sleep in the bed, it converts the land around you back to the over world. To be fair, it looks cooler than the loading screen.

However, the real issue here is that on the client Minecraft.getMinecraft().player.dimension is 0 whether you're in the overworld or the lost cities dimension(111). I was told the issue does not present itself when lost cities is on the client and server.

I am the developer for Journeymap and one of our users brought this to my attention because of an overwriting map issue when switching between the overworld and lost cities dim.

The Lost City dimension doesn't work if it is only installed on the server. This requires the mod to be on the client too.

Then why do we have acceptableRemoteVersions = "*"?

I am guessing acceptableRemoteVersions = "*" allows clients to connect to the server even if the client does not have it installed. Or, do you mean that clients without it should not be able to sleep in the bed to travel to the Lost City dimension? I tested and I was able to travel there without it being on the client as an op, and not as an op by sleeping in the bed.

Dimensions have to be registered on the client in order to work. That means that the lost City mod must be present on the client for this dimension to work properly

Because we want to allow non-modded clients to connect to a modded server that has Lost Cities. That's what that line means. Accept any kind of 'remote' (which is client-side) version. Including vanilla

I need to write a more complex checker for this. I reverted my bad fix that breaks that use case for this release.