I think maybe you should remind the teacher that he is studying in his second language, he may be fluent in English but he has been 'living' day to day in Swedish. Assuming you have been speaking English at home and Swedish at school he may be learning new vocabulary / not fully understanding.
Ask if she would do the same with a child newly arrived who doesn't speak English.
Does he know to ask for help / explanations? Does he have TA support?
In the midst of teaching it can slip my mind that some students are ESOL, particularly if they have a local accent. I sometimes get pulled up short when I use a word students don't understand, one resent example I told a student to get out the 'felt tips', she was 17, I assumed she new what they were. It was explained to her in Italian by an African student.
I'm in the midlands, I'm used to ESOL and cultural differences but occasionally it can throw me. Depending on where you are in Wales the teacher may have never come across child who has not been educated from day one in their first language.
I think it might also be worth having a discussion with the teacher about basic skills. I moved primary schools a couple of times. At two I was expected to write in pencil in print, you got a fountain pen at Xmas and the term after learned to do joined up writing ready for middle school, then I moved to a school where the children were all using biro and had been doing joined up writing for 2 years.
Little things like this can really slow you down. He may also be getting distracted with other children's chatter or with understanding the local accent (I'm assuming you do not have a welsh accent, apologies if I'm wrong).