In the novella I'm working on my antagonist is a Russian mobster. I always love when characters lapse into a second language in stories cause it always makes the character a bit more authentic. Especially when it can confuse other characters not knowing what the character is saying. I don't want to always rely on the fallback - he said something in Russian. However this would be so much easier in French. For Russian I'd have to download some sort of Russian keyboard and in the end it might look totally awkward. What I'm thinking is, what if I type out the word like how the English would pronounce it - For instance *sshole - would be mu'dak. Has anyone seen this done?
That's called transliteration, and it's pretty common IRL as well as in fiction from my experience. Would not bother me in the slightest.
You could use google translate instead of a Russian keyboard, but writing it in english would give much better flow to the text. I do this in real life, as some words just lend themselves to phrases more readily than English. "bu hao" sounds so much more meaningful than "that's bad" "Je ne sais pas" than "I don't know" Che? than "Huh? / What?" So I would definitely say go for it.