I was watching this video and I realized that all the instruments on the Soyuz spacecraft is in Russian. So how can the non-Russian crew use those instruments? Do they also study Russian before the launch?
They all need to study English/Russian as part of their basic training, and have some basic technical grasp of the language to suffice for communicating with crew-mates and handling some equipment.
There have been cases though, where cosmonauts, mostly, had poor (or under the 'desired' level) English language skills. In these cases, this has been amended by having another cosmonaut in the team with good English language skills, or having most of the astronauts speak basic/good Russian.
I remember the case with one of the last space shuttle missions to Mir station before it was decommissioned, where a cosmonaut (can't remember his name right now), could barely speak English, and they bypassed this by having the rest of the crew communicate with him in a mix of basic Russian and hand signs, and he also had another cosmonaut to rely on.
His very presence on this mission was very polemic, but this is aside from your question, as he kind of 'forced' himself into the mission by some political leverage. He was one of the chief designers of Mir and wanted to see it once before it being de-orbited.
There used to be quite a lot of language problems right after the crews started to be international first on Mir and then ISS. But today, the cosmonauts are expected to speak several languages, whichever country they come from, as they are usually crazily well educated people anyway. As for the Russian parts of the ship, the the non russian austronauts selected for an ISS mission go through 2 months training to get familiar with the russian parts of the station and to get basic knowledge of Russian language.