Please test this
client-side patch
https://www.dropbox.com/s/6y8jpxo87g1i4pl/galacticraft-1.6.4-2.0.11.978 - BungeeCord patch test1.jar
Note: On your client, put this in your /mods folder for B-Team, but make sure to move the existing
galacticraft-1.6.4-2.0.11.978.jar out of the /mods folder before you launch B-Team otherwise you will get a duplicate mods error.
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What this patch does:
(1) Prevent the client-side crash when switching servers if the dimensions are wrong (it will just log an error message instead)
(2) Detect when you switch from Server A to Server B through Bungee, and reset all Galacticraft dimensions client-side.
I'm hopeful that (2) will deal with the issues you described (the creation of DIM-2 on Server B, and the Moon-walking on the Overworld type issues) but without thorough testing I can't promise.
I have tested this patched client on a public B-Team 1.0.10b server today. But, I don't know if this will fix all the server-side issues - I didn't play long enough to create a space station and I don't have access to the server files to watch the dimension folders being created. I think it's best this is now tested by a server owner/admin who can watch to see what dimensions get created.
If you watch the console client-side you will see two "GC *** SERVER CHANGE DETECTED ***" messages each time you switch to a new Galacticraft server, don't worry about there being 2 messages there, that is just Galacticraft Core and Galacticraft Mars both detecting it.
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I understand that it would be better if we can make a server-side patch but that probably isn't going to be possible for this one (I'll discuss with micdoodle8 before we rule it out completely).
So, assuming this test patch fixes the BungeeCord issue, it will need all the clients to have it. All that we can do is make a new 2.0.13 build of Galacticraft, and then server-owners and players will have to persuade the modpack makers to include that latest GC build in the modpack, so that everything will eventually be fixed after the next modpack version update.