Hi,
we have been living in Wengen, Lauterbrunnen valley for 11 months. My son turned 9 just after we got here and my younger son was 5.5 years. He had only been to kindy, not school before here. My older son went to kindergarten in Switzerland the year he turned 5. He seemed to understand a little by the end of the 10 months but mostly only knew numbers and basic words. BY the time we arrived back in Australia a few weeks later he said he could not recall much except for numbers. Later he told us he just said yes to anything the teacher said!
Our 9 year old is able to speak to most children in German in the last couple of months, which I believe is mostly due to him befriending a Hungarian boy who speaks German, no English or Swiss. His grammar is often incorrect. There are a lot of other Europeans at school so mostly German is spoken. The teachers say he understands most things now. It did not help that a month before we arrived an English family with 2 boys the same ages as our 2 arrived. Good for having a friend each, not so good for learning German

. Also, our 9 year old was very reluctant to learn German. He hated practising and also hated my husband speaking to him in German. He is actually enjoying it now, thanks to his teacher and now having a basic understanding.
Also, our 9 year old had 4 different teachers in 5 months which did not help him integrate well, but his teacher since August has been amazing!
Our 6 year old has always been keen to learn German and would always come home and ask what words or phrases mean, but he does not seem to be able to have any conversations yet. His best friend is English, and their other friend speaks English almost as well as he speaks German.
They are loving their life here very much, lots of freedom compared to back home.
My 9 year old wants to stay here long term, our youngest would be happy in either place. Where are you from? And where were you living before?