They also make for great storage. Using solar to make a hydrocarbon fuel which is turned into electricity in our existing fossil fuel infrastructure seems way more plausible than spending trillions on batteries or pumped hydro.

Yep.

Batteries aren't great for super-cold areas. Pure hydrogen, my understanding is that it's pretty much impossible to make a 'leak free' tank. So for things like backup power generation there is an additional challenge. More thinking about need to top off than risks, I'm not qualified to speak to whether such a tank would be a risk.

I don't think that leakage is a serious issue in high-pressure hydrogen storage. The tanks used in hydrogen fuel cell vehicles have leakage rates of a few mL/minute [1]. The first generation Toyota Mirai has a storage capacity of 85000 standard liters of hydrogen. It would take tens of years to leak out a significant fraction of that.

[1] https://link.springer.com/article/10.1007/s42154-020-00096-z

Right battery chemistries with right thermal management and especially right software would work well also in cold climates. Bjørn Nyland from Norway tests a lot of this stuff on youtube.