Very happy to give any info I can.
DS1 has just turned 7 and is in the English section. We could have chosen French as he is bilingual but I knew I didn't like the French approach to education and was pleaed to have 'escaped' France for that reason.
Obviously I can't comment on Lux system, but one of the many factors in our decision was that my impression was that it was more along the lines of the French system (though the main issue was languages as I thought arriving at age 6 and suddenly having to face 2 new languages was a big ask for a shy child).
Because the teachers are sent from the UK or Ireland, their approach to discipline is much what I would expect in an English-speaking country. No 'punishments' as such - I think their name goes into a cloud on the blackboard if they are naughty, and then into the thunder if they are really bad. Occasionally the boys have been denied use of a football at playtime for a few days if they have been using it inappropriately or kicked it into a tree or something. There is one child with behavioural issues and the teacher told me she was shocked when she had to count down for him to do something (and a bit worried he wouldn't comply). So pretty minimal really. What punishments has your DD had?
I had heard lots of horror stories in France about teachers being really nasty if kids underlined something in blue pen instead of red (and vice versa) and really setting out to humiliate the children.
The other thing I wasn't keen on in France was that the kids get a lot of homework from age 6, whereas here it has been fine so far - just a reading book each day in year 1, and now a reading book from time to time plus a few spellings once a week and a bit of maths once a week.
Which section would your DD go into at the European School?
I do feel for you - it's so hard when the system is so different from your own, and hard to work out the best choice in Luxembourg with all the linguistic/integration issues.
Oh, the other thing I would say is that initially I was a bit put off by the size and anonymity of the school, but in fact it is like a whole lot of tiny schools all joined together. In the English section of our school there is only one class in each year group, so the kids stay together and even after just a year here I know almost all the parents.