is it ok to store quinoa, rice, lentils, barley, farro, kasha, black beans in the fridge?
If you have the space there's no reason not to, and some good reasons to.
For one thing, it reduces odds of various bugs infesting (or hatching out if the eggs are already present.) For things like ground whole grains (whole wheat flour) it also slows rancidity - though that should not be a problem for the whole grain.

Personally, I'd need a walk in fridge (which I'd love to have anyway) to manage to have space to store dry goods in it.