Switching of languages works wrong
Version 0.9.3.1
I guess when needs to switch from language 1 into language 2, then needs to switch into English first and to switch into language 2 the next. Right now after switching into language 2 we see some strings in language 1 still, but they must be English.
For example, we can see Russian translation for French language:

I think the easiest way to deal with this is to require a restart after switching the language. Language is not something you switch frequently.
Restarting is last centure way.
I know from my own experience that it can be VERY painful and time-consuming in Qt to support live language switching. You have to make sure that every widget is updated, and it can take forever to track them down in code and add specific callbacks. The amount of work and testing required for this far outweights the actual benefit.
Restart is a perfectly reasonable answer to that. I'd just make a simple message window pop up after a language switch.
Simple is good.