I've rarely seen the Glass Lizard on display in this exhibit, however I do often squint hard at the glass and look at the behind the scenes enclosures, where there are quite a few individuals
In the display tank the Scheltopusik is usually under the sphagnum moss, but (at least for me) can usually be found if I look. There are quite a number of them in the "off display" tanks inside the house as well - most easily seen through the side of the house where the Giant Millipedes are, although the tanks inside do get moved around a bit.