The environment in a fridge is dry due to the evaporator sucking moisture out of the air due to the refrig effect , similar to an aircon the system pulls moisture out as it cools down and this moisture then runs out a drain somewhere.
The time moisture will appear is when you open and warm humid air floods in and condensates in cold things such as a keg or say gas reg.
It's only brief and occasional and when you shut the lid , the moisture will soon disapate and your reg will dry.
I can see no issue with your regs in the fridge, possible issues will arise if going into freeze territory etc.
I had my regs in my old keezer for 10 years , no issues.
I keep mine out as my new setup has space, plus I get extra keg inside instead of gas bottle .plus I use it for other things as well as adjustments are easier etc
But for cosmetics or space, no worries. But if you can put them out, better.
Cheers