I don't think it's possible to change the lobbies properly without some kind of sorcery.
But if you do not mind to get lobbies exactly like they should be (some effects will be missing), and just want to bring back old feelings thanks to an illusion, it is possible to do this by swapping some files.
Firstly, if you don't use it, you have to dl and use the edited CRC file to prevent the game crash :
viewtopic.php?f=3&t=108(1st link in the 1st post)
Then...
"Replace" e02e3ef39240260d9070a4e83649222b with 805591d4504c049238dffaa00ed90267, and b1c695aba1a7839863b48f81f24df749 with 80f62685f5c151ebee0a1e7eb7027554 to hear the Fireworks Lobby music or 1d069d3165e4a2bf2a32d46f7c05bf49 for the Holy Light Festival Lobby music.