I play in this datacentre and can confirm that there are pretty much zero English speakers around most of the time, and those who don't also speak at least a little Japanese tend to struggle. I think I have met three other English speakers ever in DF, excluding those in my own FC. If you don't speak Japanese you would probably have more luck using Party Finder as some curious/tipsy Japanese players will probably help you out if they know what they're getting into in advance.

A tip if you do speak Japanese and want to persist. There are two places to pick your language - the search screen with your own player info and your duty finder window. You need to set the latter to include Japanese if you want to queue with Japanese speakers. French and German will make no difference as I've never seen anyone flagged with either in DF here.