Just because rubbing the debug button with a pencil yields interesting results doesn't mean rubbing any ol' thing with a pencil will cause anything special to happen other than the destruction of your tam.
I can guarantee that even if something DID happen (other than your tama not working,) it wouldn't be stepping back a version. That'd be a waste of space, as including the ability to revert back like that would mean having two tamas' worth of electronics and programming in a space designed for only one tama's innards.
Granted, when debugging, characters you can't get in the ordinary game appear as choices, but those are small changes. And granted, being able to revert back would be a neat feature... but why would they leave it in there without publicizing it and offering it as a feature in the manual?
Being able to test and see which characters available by "debugging" is a feature that could be utilized by the factory to see that they're all there, I suppose. And the hypermode would allow testers a compact view of a tama's lifespan, which would be valuable for testing. If they fould problems, you could say it needs to be "debugged."
Adding a whole version to the thing is unlikely, though, as that's just taking up space without any value to the creators if it's not offered as a feature to the general public.
In conclusion, don't touch anything other than the 'DEBUG' button.
