I had the game installed in polish (which forced the Galaxy client to download polish patch after initial installation in english).
Then I tried to patch to 1.1 from within the Galaxy client but the installation got stuck at some 92% or so.
So I interrupted the installation and downloaded the offline patch installer. The installation went OK and now I can enjoy version 1.1.
That's all pretty swell but...
But the game, after the patch, turned back to english.
And now I'd like it to switch again to polish and there's no way to do so. The Galaxy client is stuck at 3% of "deleting" patch download so I cannot use it to switch languages (it still says it's in polish but that's kinda understandable as I installed the patch from "outside" of the client).
Anything I can do?

Go to the game's installation folder and open the file "goggame-1423049311.info" with an editor. Replace "English" with "Polish" and "en-US" with "pl-PL"

It worked! Great! Thanks!!!

You're welcome. :)

So I am not going mad? (Well, I probably am, but it's unrelated to this.) Someone else had to do this, too?

YES thats'it 8)