Since your DD is very active and engaging in sports, I think that she is eating what her body is craving - fats, carbs and sugar. All that energy has to come from somewhere, after all. I don’t think 8 crackers with butter is necessarily wrong, she clearly needs the energy, but perhaps you could have healthier , more accessible snacks, so fruit, high protein yogurt, cheese slices, etc. I would also say that crackers with butter are quick, easy and no thought. Even making toast, you have to get the toaster out, wait for the bread to toast, then butter it, etc., and you go from a “quick” snack to something more time intensive, even if the actual difference is only minutes. To a 10 year old, these minutes are hours!
I am more concerned with her taking the treats up to her room and hiding the fact that she’s eating them. Does she feel that you would disapprove of her eating the treats? Are treats “policed”, in terms of after you clean your room or do xx chore, then you get a treat? Has she ever been told off for eating a treat, such as 10 minutes before dinner, or perhaps you might have said at some point that if she hadn’t eaten the treat, she would have eaten all her lunch/dinner? There’s a lot in the media about “good” food and “bad” food and she may be subconsciously absorbing those messages, so perhaps a chat about food = food might be a good idea, so that any internalised shame is dealt with now, whilst she’s still young. I’ve always told my children that if the food is there, they can eat it, unless it’s packed lunch food, and all of them at some time ate so much chocolate that they felt really ill and that was okay too, because they learnt that chocolate = nice occasionally but it needs to be eaten in moderation.
Because I live in a hot place, I tend to airfryer a joint of meat/chops/steaks and have a platter of different salad veggies, potato/rice/pasta salad, coleslaw, pickled veggies, beetroot etc., and I also will make some “fancy” artisan bread or rolls to go with it (it’s easier to cook in the middle of the day when the solar panels pay for the aircon!). DH and DS will demolish the bread/rolls as well as eating the carb salads, as they have jobs where they are on their feet all day and walk a lot (~30,000 steps per day). They will also then have cake or fruit pies or a chocolate bar (though chocolate is not chosen often), fruit or biscuits afterwards. It sounds a lot but being physically active, it really isn’t. Perhaps offer some bread with dinner, so DD is having something to fuel her sports before the activity.
Try not to get too stressed or anxious about this though, as she will pick up on it.