OK, so anyone, just about, could be called Olaf. In principle, anyway. But occasionally I feel there are more unfortunately named Olafs in non-Nordic language fiction than there are actual boys in Sweden, bearing that name.
Yes, Sweden. If you at least could make Olaf Norwegian. If you did, I wouldn’t even know what age he ought to be. (Although someone else would.)
There are skills in naming people. In your own language, or more narrowly, within your own area, you probably know who might be called what, and how old they are likely be.
I don’t know whether to blame Olof Palme. There are two main facts about this former prime minister. One, his name was Olof. Not Olaf. And he was ‘old’ even when he died, by which I mean a boy Olof would not be someone today. But there is a real fondness among authors for naming their Swedish characters Olaf. As they have every right to do.
The other thing that sets my teeth on edge is a surname ending in -[s]sen. Doesn’t matter if it’s single or double s. If the letter e follows, they are either Danish or Norwegian. Originally, I mean. I went to school with a Jensen, who was pretty Swedish, apart from his Danish passport.
Sweden has so very many -sson names that it’d be a shame not to use one of them. Johansson, Nilsson, Svensson, to list but a few of the very commonest. (This is why I can’t take Scarlett Johansson seriously.)
If in doubt, ask a Swede. Find a phone directory if possible. Try to avoid the immigrant names. I believe Philip Pullman found Serafina Pekkala in a phone book. Wise man, because it rings (pardon) true. At least to me, who will have to count as a foreigner in this matter.