Currently in AccountUUIDs you use a new cache file named "GoreCore_ServerUUIDCache.txt". However, every server already has a "usernamecache.json" which is exactly the same thing but from UUID to username instead of username to UUID. My suggestion is to remove the "GoreCore_ServerUUIDCache.txt" and use "usernamecache.json", something I can implement unless @CrowsOfWar knows something I'm overlooking.

@CrowsOfWar bump

@mahtaran good idea, it looks like the GoreCore cache is unnecessary.

I'm not at my computer right now, but I did a bit of research and maybe the pre-existing class net.minecraftforge.common.UsernameCache might work? This could potentially be useful to avoid manually reading and parsing the json file. Of course if you were planning on parsing it yourself, that could be a good approach too.