Great mod but the Planet Sizes aren't proportional so changing the size of Mars from 13 to 9 doesn't make sense because yes Mars is roughly above 50% of Earth (size=16 in Stellaris) size, but size=9 is way less than 50% of size=16.

Basically a size=20 planet is not twice as big as size=10, it's much bigger than that. I don't know the exact proportions work in the game, it seems a size=20 planet is at least 4 times bigger than a size=10, but I cannot seem to find exactly how much.

And then when it comes to planet sizes, a size=20 Star > size=20 Gas Giant > size=20 Planet, but this size=20 Planet will be bigger than its size=20 Moons, which are the same class actually, both can be barren or habitable. So proportionality obviously doesn't work there either.