hi, How is she doing in your set up now?
Its normal that they burrow themselves.
Kaloula pulchra is quite a hardy species, as I live in Hong Kong, I always see these guys hiding in underground pipes.
They can tolerate wide range of humidity and if you really wanna see it not burying itself, you can increase the humidity of the bottom of the substrate (or even make it wet thoroughly) so that it feels too wet to be burried. It will get straight out of the mud and come out to breathe and will find another spot to hide. Make sure you get rocks and other things for them to hide, as they feel more comfortable hiding in substrate under rocks or plantations. Hope it would help. Good luck and enjoy!