I need some expertise badly! I have a contractor that orginally said they were going to install hardibacker for the shower and tub area and instead installed the purple moisture/mold resistant drywall.

Their tile subcontractor installs a shower by meshing the corners and then spraying the base and walls with redguard waterproofing. Once dry they start installing tile with thinset.

I'm putting up 18X18 travertine in the shower. What came out of there was mudded with chicken wire originally.

I have another tile contractor I've used before that does high-end showers a lot and they only do the mud version with chicken wire.

I'm concerned about having leakage at a later time.

What is the best way to go and have you ever heard of this method because no one else I've talked to so far has?