Apparently the global version of the game will only have English audio, but other language text. Japanese version will have Japanese audio, unclear whether it'll have other language text or not, as the question that prompted the answer only asked if there was "a single global server".
Of course, to the one asking, they meant global as in world-wide. But to those with experience with mobage, global means "all non-Japanese markets". However, it was asked to the Japanese department, so perhaps it will all be on one server.
Source for those curious. The best guess for why this is the case is in order to keep the file size as small as possible, which I guess makes some sense if every character is talking at some point. Though it should've been simple enough to just have a prompt asking which voice pack to download.
This being the case, assuming it's the world-wide server, I'll just go through qooapp to get the Japanese voices and then switch to English text asap.