I was also using those books 15 years ago. They are for adults. They are incredibly boring. The focus is on rote learning of grammar and vocabulary. It is quite possible to complete many of the gap-fill grammar exercises correctly without actually understanding the meaning of any of the sentences

. The whole approach is very, VERY outdated.
I would guess that the teacher is using this book because he/she knows it off by heart which means there is minimal preparation involved, minimal effort. It's so easy to turn up for a lesson and plough through the book one boring page at a time. It doesn't encourage communicative activities. In fact, it doesn't encourage communication at all. The language is not representative of the kind of language a 8 year-old child needs in order to communicate with peers. So, it's pretty useless for giving a child the language it needs to integrate with native speaking kids.
There is, in my opinion, little justification for using ANY FFL textbook with a class of second graders. My suggestion: chuck the books in the bin and get the kids DOING stuff: playing games, role play, doing other stuff in Finnish (eg art, sport, music, maths).
I would also guess that the teacher is 50+ and has no qualifications in teaching foreign languages. Probably a semi-retired Finnish mother tongue teacher. At least that's the raw deal that my kids got when we arrived here and they are still paying the price of that mess up.
In a nutshell, I would go straight to the Rehtori and if he/she does not listen, then go to the School Board (parents have representatives on the School Board), then take it to the municipality level.