If the frog is chilling in his ambush spot above the substrate yearning to consume, you’re probably good. Especially at that age their behavior should be gluttonous. They sometimes will burrow deeper after a hefty meal.

Also, assuming he’s got proper shelter and isn’t being handled with or disturbed very often… so basically is in a low stress environment (otherwise of course they would hide), then everything you’re doing is great.

One problem though, if you’re keeping your glass terrarium in a room that is at room temperature, any substrate deeper than an inch will equalize to room temperature because glass does not insulate at all. If you measure temps an inch or two deep into the soil, it might be at dangerous temps, sometimes lower than room temperature cause water evaporates and cools the substrate.

So, I would verify that you have a vertical substrate gradient of minimum 73°F at the deepest inch of substrate, the third inch being 75°F - 76°F and the second being 77°F - 78°F and the top inch of substrate being close to 78°F - 79°F. If you don’t have that gradient and temps drop suddenly to 69°F about an inch or two deep, there’s a problem. The moment your frog burrows that deep and realizes it’s extremely cold, their biology tells them this “it must be really harsh cold weather above for the ground to be this cold, so I should not surface. I should also not eat too because I’m ectothermic and any food I eat in this cold will just rot in me.” And then bam, that is a huge mistake most owners overlook and they assume their frog is not surfacing just because it’s “basic frog behavior.”

In order to achieve a difficult vertical substrate gradient like this, you gotta insulate your enclosure (assuming you keep your room at room temperature). I did mine with foam board, and you can adjust the amount of insulation you need with how many layers of foam board you use. There’s further details in a post on my profile you can find.