I think it's possible, yes, but results won't be as good as they'd be if they were OMSI generated mountains. And I had understood that if this is not implemented is because of troubles while programming, so my complain was just for saying something.
And answering you, for people whose Blender modelling skills are not enough for making something decent, thinking about modelling a mountain is quite...exhausting (this is not the exact word, but you understand me). So, for us, having a tool which allows you to make a tunnel through a mountain is better than having to model a mountain and the tunnel behind that. But doesn't matter, another challenge to beat!