I recolocated the slickster's tamed egg into that refrigerator. After some cycles, they turned into tamed baby slickster, as expected, but their wildness don't increases (or "docility" don't decreases).
As you can see, i have a slickster 46 cycles old and is still tamed. (maybe this happen with all creatures, i didn't test it)
Steps to Reproduce
recolocate a slickster's tamed egg outside stable and wait to grow
This issue has not been confirmed by a developer yet.