AFAIK there was no definite answer by those modders who wondered about this when that potion was introduced. Buzzler in particular wanted to find out. But as many people have done this in CAS so far with nothing bad to report, I'd say that it might still cause your computer to explode, but the cat should be safe at least.
I myself have only used those options in CAS that the Young Again potion or the corresponding Supernatural elixir offer, i.e. elder to YA or adult to YA. Aging a YA down to teen at least did cause some confusion for the game (teen was still listed as having graduated, for example), and have never messed with child to teen and back. Maybe you should just try it; but don't forget to post pictures