Finnair obviously only shows you Finnair points. If that’s the currency you want to collect, it’s fine, otherwise it’s useless.
WhereToCredit is usually very reliable. But it only shows redeemable miles.
If you don’t care about Oneworld status, it’s probably best to credit these flights to Alaska Mileage Plan.
Edit: I see you’re based in the UK. Just credit them to BA and you’ll be fine.