Wouldn’t it make more sense to call “five russians from the chechnya region” five chechens?
Or Muslims from Chechnya.
Most sense to say, “five Muslims”. That is the only identifier that matters.
That depends on what political angle you're trying to sell. If you want to pretend the policy critique offered by the Front National is invalid, that there is no problem with mass immigration from Muslim lands, and into the bargain get a free propaganda point against Russia's resistance to "the European project", then "five Russians from the Chechnya region" makes perfect sense.
Russia has a long history of control over Islamic terrorist organizations. The presence of individuals from Russia, even Chechens who have also been used in other Russian conflicts, is immediate cause for suspicion.
Russia has an interest in such terrorist attacks— they take attention away from Russian terrorism in Ukraine, and they strengthen Russia’s front parties in Europe. Russia has been working hard to infiltrate and control the faux-Right wing in Europe. They already control the Communist parties.