Try a bar where the musos hang out. It's a pretty safe bet that the scene is tolerant and that English is understood,
My local is "Celsius" in
Bockenheim, in the Leipziger Strasse. My band are regulars there, and two thirds of us are Brits. Plenty of lesbian guests there, all the staff and pretty much every customer there I ever talked to had a very decent command of the Queen's English. (see what I did there? hahaha!)
Not really LGBT, but mixed and easy going.
Similar in other parts of town: "Backstage" in the Rohrbachstrasse,
Nordend. Bit sort of old school anarcho-punk. Or "Nachtleben" in the town centre on the Zeil. More sort of up-market.
Don't really know about strictly gay places, I tend to avoid them just as much as the strictly straight bars.
Cheers!