my dd1 is almost 10 and sounds like a similar child.
she currently does 3 dance classes (last year was 4, but we moved house and i cut one back) and although this year isn't an exam year (she took g3 exams last year) they have a big show coming up. she plays ice hockey three times a week and is a 'lone' guide. she also is in the school choir (can't imagine why, as tone deaf lol) so has lunch sessions with that. our school only have 20 minutes for lunch anyway though, so none of the 3 ever manange to really eat lunch.
she has also been put forward for the regional 'gifted' programme at school and has just won the school spelling bee, so is off to the regional comp for the school next month. this term we are taking a break from swimming lessons, largely as we can't actually fit it in lol (have two other dcs). we are also trying to make the most of skiing whilst the snow is here!
she's well balanced, happy, and not in the slightest bit stressed.
tbh i am more worried about your comments re g3 exam than the amount of stuff your dd is doing - 'we have told her it will be a major achievement'? it sounds as though you might be in danger of putting the pressure on her yourself? i do understand it was a response to the skipping g2 thing, and designed to make her happier with not getting honours, but may have the opposite effect?
fwiw, i'm quite relaxed about dance exams. dd1 loves to get honours (as does ds1 lol) but tbh she isn't going to be a professional dancer, and it really doesn't matter that much in the grand scheme of things.
so, i think it depends on your child etc etc. my dd1 is quite happy, and has plenty of 'down time'. take your lead from her - any signs of feeling the pressure, maybe ease off a bit.
i'd quite like more down time myself, but can't see it happening any time soon