Two more updates this week:
This is my version of Montana's flag, based primarily on the flag of the city of Denver. The biggest issue was the poor contrast of the silver, which is too light and from a distance would be almost indistinguishable from the white snow caps. In response, here's a fix:
The silver (really more of a gray) is darker now, and does a much better job of standing out. Not everybody was a fan of the snow caps either, but I still kinda like them.
And New Brunswick:
All I had done to the original was get rid of the lion that formerly resided in the red stripe. But now it just looks like something used to be there and it doesn't look natural. It really should balance out the blue of the waves, rather than dominate it:
It now is better balanced by the blue/white sea, plus the flag is now more elongated, a common trait of Canadian provincial flags.
Thanks to Voron X and Francis for their input.