Brenononon

However during that time, the survivor would not be tunneled, now would they? It's an anti-tunneling perk.

That'd be a really cool idea, but they'd have to make a lot of deals with Stephen King. As well as that, with the current lore in place there would be a lot of plot holes that are hard to fill.

You can't get banned just by using them because the anti-cheat can't detect them to my knowledge, but it's an unfair advantage so if the developers or moderators somehow found out from videos or screenshots of your desktop, you might get banned. TL;DR: Bannable, but almost undetectable.

The developers have said in a Q&A that it's highly requested, but they don't have plans for it.

I can't answer your question, but I'm assuming they have chat logs. It'd be so easy to fake screenshots and get innocent players banned. Just remember to also report the player through Steam!