Been living in Montreal since 2006. Married a local.
Still can't speak french beyond a 3 year old level. And I was a straight A student in school.
Learning a new language is not easy for a lot of people.
Absolutely. I think some people are underestimating the difficulties with learning a new language, even if you are able to immerse in it on a daily basis. Some people are simply better at learning languages than others. The girlfriend was able to learn Mandarin within 6 months of being in Taiwan but she also spoke Cantonese fluently with her family, which is not easy (I know many Mandarin speakers and Cantonese speakers that cannot learn the other language) but definitely closer than Finnish is to English. A friend of mine has mastered English far beyond what most native speakers will come close to in their lives and only started learning English at around 8 years of age having come to Canada with his Mandarin speaking family.
I took French up to and including high levels of it in High School and can hardly speak it to this day. Learning German in university for a couple of semesters and my own personal study of it through exposure to film, literature etc and using an app to bolster has made my grasp of German much better than French but this is with less time overall spent on it and as an older individual (learning additional languages at a young age is definitely much easier). For me, it just clicked. Perhaps it has a lot to do with greater interest in the language. Once you get to more complex forms of any language you can start to get bogged down and stall in learning it, which is where I'm at now. I was also a straight A student but languages are a different beast.
To boot, French and German are both Indo-European and English has been heavily influenced by both. Old English is somewhat of a stone's throw away from Old High German (largely in part due to Anglo-Saxon invasion and subsequent influences of Germanic populations in England over the centuries). Latin and Romance languages had a vast influence on English as well (Norman invasion, French imperial influences before the rise of the British empire etc).
TLDR In Puljujarvi's case, Finnish is about as far from English as it is from Non-European languages. It belongs to the Uralic / Finno-Ugric family and has very little in common with Indo-European languages. You might as well ask him to go play in China and learn Mandarin. It seems like he is grasping the language better than last year. I think his problems are more confidence and figuring out the NHL game in general.