Maybe they could get a small bonus to resist cold weather?

For the Ósterkligr, I think the bonus to constitution is pushing it. It'd be more balanced if you raised charisma to -2 and removed the con boost.
Alternatively you could just remove the constitution bonus and scent, then create a 1 level transition class that turns them into a true bjorn. It could then be used to represent both Ósterkligr and Aeska.