Hello, could you be more specific about your warning. As this forum looks to help folks understand how to avoid common mistakes and improve their reptile keeping experience. Some details would be helpful.
As a side note: I have over 150 enclosures for Tokay set-up exactly as described with the cork bark leaning against the slate, that is leaning against the side of the glass.
90% of my eggs are on the slate facing the bark, and the other 10% of our eggs are on the bark, facing the slate. 100% of both parents 'nest' in this area as do the offspring. This is the core structure(s) within our Tokay enclosures. The slate and the bark are sturdy enough to stand up to the movements of large Tokay, they stay resistant to fungus and rot, and are easy to clean. There is enough humidity within the hide/nesting area to produce very high hatch rates and one can observe them, and they you, without any disturbance.
Obviously there countless ways to house Tokay, as long as they meet their specific needs, it does not matter to me. I can say that I've suggested this set-up and it has had good results for several others as well.
All the best,
Michael