All righty, I am officially perplexed. I thought for sure I had this licked, not so.
After a full 3 days of curing, doing everything by the book and then some, it has crackled worse than ever the instant clear was applied to the etch.
The only one of this series, posted above, that came out perfect I cleaned and didn't pay attention to cure times, probably around 3 hours. As you can see, it reacts the most, if not exclusively, on areas where etch meets paint. Painted areas alone seem uneffected. So apparently this clear must be creeping under the paint around the etches and causing havoc ... Though why it didn't do that with the one above is the question.
The white one too, just cleaned and didn't pay any attention to "proper" cure times, and that came out almost perfect.
It is either just blind luck, of my cure "window" is far from what the paint can suggests. [And granted, I know this doesn't quite approach the level of definitive scientific experiments].