Hi there. The usual suggestion for escaped treefrogs is to put out a few bowls of water. Dehydration is a typical threat (and other pets) so the hope is they will turn up in the pools you provide. You might consider doing this just in case they aren't in their viv. As already mentioned, there is a still a good chance they are inside and are hiding very well- their first defense is to not be seen and they can do it very well. I know I had a few panic moments when I first got my American green treefrog- he found spots to hide in his viv that I hadn't considered.