Very Interesting r3n, let me tell you my opinion on this.
First off I quote myself when I said that the current shield has:
heraldic oddities and violations (an irregularly shaped escutcheon pasted on a plain traditional one [that's the yellow/golden thing], two different azure tinctures, and a single charge in base [that's the laurel], and on waves... All of them very unlikely in traditional heraldry for a series of reasons).
Heraldry doesn't normally let you do those things because the result is difficult to "read", is like using bad orthography when you are writing.
Now the rest of your suggestions:
However, the color pattern in the shield in Lennart's design isn't working for me. I think the red layer is disproportionately large. This impression is made worse by the fact that the red layer is at the top part of the shield, which has a larger area. It may be better to add another blue wavy stripe before the red field begins.
Funny fact: the wavy area (white and blue) is actually larger than the red one.
The Field is divided in two parts similar in size, and adding another blue wavy stripe (just like the original has) is again a lesser rule breaker, especially because it would get in contact with the red above, and contrast wouldn't be so sharp, that's why you put colours on metals or vice versa but no colours on colours or metals on metals.
In particular colour blind people have problems to "read" a coat of arms or flag when rules of tincture don't apply.
The red part?, the usual practice in heraldry would be to put an emblem (in this case it would be a metal, gold or silver, emblem) but the original is empty and it creates kind of a nice contrast with white and blue colours of the flag. With a metal emblem on it, it wouldn't look so big, it would look more "balanced" if that makes sense.
Now the background, that frog-cross you mention, it's also not my favourite feature. For some reason they chose the Coat of Arms of Arévalo (a village lost somewhere in Spain) as an inspiration. (edit: did the research, and it's supposed to be a compass rose, which is kind of appropriate for TNP) But I kept the whole thing because I didn't want to create something so different from what we've got.
If I had to make a new design from scratch I would do many other different things, the result would probably look nothing like the official one... But at the end of the day I was looking for a flag that represents the region and not only my taste. I was trying to compromise between good heraldry and TRADITION!... Although I would accept the idea of doing something completely different if you want me to.
Thanks for your comment r3n! hope you're doing alright