Tried to seduce a girl who spoke very fluent English but was nevertheless foreign. I usually have pretty dry humour, and noticed that it wasn't translating well across that language barrier in a variety of ways; sometimes she'd take the joke literally, sometimes she wouldn't pick up on the cue to respond humorously, and other times seemed like she wanted to respond with a joke but wasn't sure how (and again, I got the sense this uncertainty was language-related).

I tried making my humour a little more obvious each time I noticed this, but it didn't really work. Actively trying to figure out a way past the language barrier also got in my head, making me feel "less natural", which didn't help either. Can you give me any tips or advice for dealing with this situation in future?

I will note that lack of attraction almost definitely wasn't an issue - we were holding hands, touching a lot, lots of eye contact, lots of contextual IOIs, got close to a kiss before some (unrelated) resistance, etc. It genuinely seemed to me like the language barrier was responsible for the humour falling flat sometimes, rather than any lack of attraction.