Looking out my window, my view of traffic lets me see numerous cars go by in excess of the posted speed limit. Seems nearly everyone goes 'a little bit' faster.
I have yet to see an accident that could be attributed to going only a few miles over the 'limit.'
Still, that doesn't make it right. Nor will it get you off a ticket, should you get one.
I have not seen a problem that I could attribute to having the wires distributed as you describe. Indeed, I have never seen such a distribution done. Maybe I've been lucky, but every three phase lighting installation I've seen has had all the circuit conductors contained within the same 'wrapper.'
You've got an installation that violates code, and makes things the very devil to sort out. The correct thing to do is to fix it. If that means running another cable, so be it.
My failing to encounter such an installation, combined with the lack of problems on the site, does not make it right. It needs to be fixed.
