I think these are slang words you may heard them in a movie ,song or a series. مجي ؟ I don't know. روحان ؟ I don't know But مرواح I think it means "gone" like when you say he's gone.

Is it colloquial? مجيئ بإضافة همزة تكون بمعنى قدوم مرواح على وزن مفعال مثل مقدام منظار معطاء وهكذا :) maybe cotext is important here, can you share please?

"مجيء هو مصدر فعل "جاء = it is the noun of the verb "to come" "روحان هي مصدر فعل "راح = the noun of the verb "to go". But it is not very used. We use more the verb ذهب and its noun is ذهاب