I have used it a few times on newly acquired tortoises that were given antibiotics, but I cannot tell if it made any difference since I didn't do any kind of comparison between animals.
Several genus added contain known pathogens, which in itself isn't a bad thing. But bacteria become diseases by (unbalanced) population growth. So adding an unknown amount of unknown bacteria species to an unspecified species isn't something I would do.
The research above is mostly published by a single author in a single journal over almost two decades ago. The referred to field trails where done on commercial birds and not on reptiles. So I’m more than a little bit skeptical.
Or don't use vermiculite at all. You can use small expanded clay beads like what indoor gardeners use. Does all the same work as vermiculite and can not be consumed by neonates.
If you check daily for neonates, check for piping eggs and put piping eggs in a separate container lined with slightly moist paper towel, and some food.