While it realistically makes sense for California, they're already heavily buffed by the high-base-tax provinces on their coastline. Adding gold-producing provinces would just make them even worse.

As for Alaska, maybe one or two gold provinces would do. It'd give them an edge over their typically-more-powerful neighbors.

Quite a bit of the gold mined in California after the initial rush involved mining techniques beyond what a Medieval tech could pull off - strip mining or washing down whole hills. A few events where California gets a windfall of ducats WITH say, a decent amount of inflation + some revolt risk (to reflect the upheaval of a new gold rush) might work, but I don't think they need gold provinces.

Tradegoods were assigned by that regions' modern economy. Its deliberately anachronistic. Also, Alaskan gold is a much smaller part of its overall economy.