Found a fix for the temperature popkill issue; while you can't make events that add pop as a percent, you can make SITES that do that, so you could give frostlings a handful of events that add/remove sites according to cold scales in their forts.

The Tracker doesn't have recpoints set, so the "copystats" you did makes it cost 6 commander points. Other than that minor hiccup, I've been having a good time with this mod.

I guess if you wanted a janky solution to the temperature popkill thing, you could give them a hidden event that checks if a province is a) under Frostling dominions, b) in winter, and c) at cold 4+, and adds +2 growth scales there. That'd be enough to cancel out the popkill, and it wouldn't be entirely a game mechanics thing, I can see Frostling life blooming in winter.

Oh, one other thing that occurs to me, on closer examination: Leadership. Ice Guardians and War Maidens being magic beings is fine enough, but it'll make the logistics for them a pain when your choices are basically 20 ldr witches and the morale penalties that entails, or 40 ldr queens who can do formations and morale bonuses (which war maidens kinda want, at only 12 morale), but are also, y'know, 600g slowrec caponlies. If it's intentional, fair enough, but if not, maybe give it a second look.

Thanks for your feedback. After further test play, I've implemented some of the balance changes in v 1.01 (see change notes) you've suggested to make the mages more powerful given that they are in EA.

For a nation supposed to be primarily water and death, offcap they only random D1, and even in cap they top out at D3. That's... poor. This is EA, you know? You've got Witch Kings, Hangadrott's and Sauromancers to compare to. Native D4 is an important breakpoint for how much of a death nation you are, that's Skullface's and the big summons like Wraith Lords, but as-is their death access is so-so.

Only 1/3 of your anyfort mages having a 2 to work with also stings. At least the A1's can summon Northern Glows, but what the D1's are supposed to do without spending a fortune on skull staffs...

Last, I can see what you're going for with White Witches, but fire/water primarily breaks you into acid magic in Dominions. I'm not saying Frostlings shouldn't be massing Green Lions and hurling acid bolts, but if you feel like it's out of theme, maybe rethink their pathing and implement frozen flames another way, like national spells restricted to white witches.