Yeah the rex issue is there and there really isn't alot we can do about it right now.
Doesn't matter how you run your server or what settings you have, rex are higher level, spawn ALMOST anywhere and usually in groups ranging from 3-6.

Other dinos are having issues also, there is a spot on the map that plesios seem to overspawn. Over time they just keep spawning to the point where you will see 10-15+ ples all bunched up together depending on how long you leave them there.

Bronto spawns are messed up also, they only spawn in some places but if you dont kill them off, you will often find them in groups of 6 or more.
Ples, Bronto etc seem to follow spawn weight changes however I had to reduce ples and bronto to 0.1 weight and 0.1 limit just to slow them down.
I dont think they are following the spawn limits cause over time they still seem to be in large groups but reducing the weight makes it take longer.

Im still messing around with the dino spawn rates to try and balance things out but every time I change one dino.. it affects another. ie, reducing one,makes another spawn more so still in the process of fine tuning but its getting there.

Also I am yet to find any aquatic creatures other then coal, saber, mega and ples however I havn't looked EVERYWHERE yet.

As for the blue haze... no idea why it happens but I can confirm it deffinately happens and at times makes it hard to see. It isn't always there though which is strange.
At first I thought it might have just been an issue with fog or something but I added a fog remover mod and it didn't affect it
I dont really know about creating maps but Id say its an issue with lighting transition or filters, like when dawn first sheds light and makes things go orange. Or when everything seems a little darker while its raining.
Maybe the lighting filters which control intensity and color are bugged when conditions like weather or time or both are at a certain value or combination.
Have to wait for the dev to take a look and see. I've tried everything at my end to remove it or even affect it. For now i've just learned to play with it.

All in all though it might seem like this map is totally messed up but even with its issues.. The map is alot of fun and offers new challenges.
Sure there is some tweaking needed but its still very playable and I'm confident that at some point the dev will get around to solving the current issues.

I have this issue 2, come to think of it.

Ye , noticed this bright blue hue issue , too. Came out of nowhere. :(

Im looking for a fix for this blue hue, really harsh on the eyes.

Coming back to this map after a year hoping the overly bright sky and blue haze would have been fixed and its still there, can't play on this or skies of nazca because of this issue, a shame, looks like a nice map otherwise.

http://prntscr.com/hibypi

Its extreme.