So she eventually replied (at around 23:40 - while I wrote at around 12).
What happened is that on the day we met she told me she had just started to learn my language (while I am perfecting hers) and I told her that we could chat a bit in both languages in the future.
Now, when I texted her I didn't mention the language exchange, I just said mentioned drinking.
She replied to the text "It's the weekend so everything's good

Frankly I would like to improve my language a little bit before we start an exchange or you would be the only one talking

"
Now I have three ways of interpreting this:
1) she doesn't wanna go out with me and she mentioned the language inability as an excuse. This might also be proved by the fact that she answered 8 hours later and at 24 o'clock (as to communicate that she's not in bed yet and maybe with other some other guy or out partying)
2) she actually thinks I want to do a language exchange with her and that I am that not interested in her. This might also be due to the fact that on the day we met there were other two beautiful girls I spoke with, both of them kinda flirted with me a bit. One of these two especially - typical snobby beauty queen - was kinda pissed I wasn't giving her enough attention and tried a couple of times to sabotage the interaction between me and the girl I am texting.
3) she wants to make sure we go on a date and not on a language exchange so she's testing me to see if I want to see her regardless.
As a rule to prevent false expectations I always go for the pessimistic hypothesis (in this case 1) even if I make another move.
I am thinking about answering later today with a small comment about the language thing (like "I see, maybe we should postpone the language thing" - which I shouldn't have mentioned in the first place the day we met!!) and then asking her for drinks again, when she's in the mood.
I am kinda sure she'll turn this one down too, but I don't care, it'll help me build confidence and persistence anyway.
What do u guys think?