The flowers of the plumeria can change quite a lot over the first few years and not just from the heat or climate. To register a plumeria it needs to have flowered a minimum of 3 times and the reason is that they can look totally different from their first bloom to their 3rd or 4th bloom, sometimes even longer. As a seedling grower I have planted many thousands of seeds and watched them grow to fruition, while a lot are nothing out of the ordinary occasionally you can end up with a real stunner but it may not be obvious with the first flowering.
I have had flowers with just a touch of colour turn into real beauties in the following years while some that started out looking like they were going to be great turned into something less than first thought. Below are just a sample of the difference between first flowerings and flowerings in the following years, all these pics are the first and most recent flowering.
The first year this one flowered I could see something great and Flame as a name was easily thought of but with the third flowering it changed quite a bit, thinking up a name now is a bit harder, parent tree is Kona Hybrid.
The first few years this one flowered it was a very small flower with pale yellow colouring but after the 4th flowering it changed into a real beauty, nice orange colouring and a bigger flower, parent tree is Paul Weissich
This one again looked interesting in its first flowering, the slightly curled petals with the darker stripe up the centres with a hint of yellow had a few possibilities. The third flowering though was again something really great, she maintained the curl but the stripe had an solid one of yellow added to it, she also kept the little kinks in the tips of the petals but more pronounced, parent is a unknown thai hybrid.
Colour changes can be caused by a few different things but as you can see from these pics the actual flower itself can go through a lot of changes on its own in the first few years. This is why you need to wait before registering a new seedling, also why you need to wait a few years before naming them, you could end up with something else entirely.