I switch between languages with Alt-Shift-1 (en), Alt-Shift-2 (ru), Alt-Shift-3 (es), and Alt-Shift-4 (jp). Whenever I try to switch to Russian or Spanish, Anki freezes completely and has to be restarted. It does this every time in any window. I tried it on a fresh Anki install on my second computer, as well, and it does the same thing. Graphics acceleration does not affect it.
Alt-Shift-2 and 3 are the only ones causing this problem. The other digits are fine. Switching to Russian and Spanish via “next language” Alt-Shift is also ok.
Tried this with with 2.1.35 and 2.1.38. Running an up-to-date English-language Windows 10.