This situation right here is why I think its great when teams offer both L5 and L6 to kids. There really are kids who would benefit from a year at L5 (this sounds like one of them - if she's getting 9s on L4 bars she is certainly ready to be working on and likely competing L5 bars - and the floor and beam changes enough to give her a real step up in preparing for optionals). Sure, L6 is more fun, and L5 scores tend to be lower in general, but the L5 bars CAN be easier because of cast requirements - and it would give her another year of maturity before optionals - then to me it makes sense to have the option of skipping to L7 if she's taking off with some muscle mass pre-pubertal growth/maturity (which is what makes them suddenly get it together at about 10 - happened with my DD - low 8s on bars in the few meets she did as a 9 year old old level 6, 9s as a level 7, 8 months later...) - or do L6 at age 10, etc.
If there is no uptraining during comp season, does that mean that she and her group have been uptraining the last few months? It has to happen sometime....if she's really been trying to get to the L6 standard and isn't there then would she even score out of L5?
I agree - a strong vault score at L4, while wonderful, can mean a lot of things...and height is one of them! If she's a good vaulter and ALSO a good tumbler with tight form on beam, then I'd say moving might make sense...That was where DD was - bars was just behind and she only trained old L6 for a month prior to competing - by the way, I thought her coach was crazy to have her do L7 the next year - until I saw her compete it....and as she went through puberty her bars have suffered again as she is a strength bars worker, not a swing kid...it kept her from Level 8 this year. Coaches do usually have good reason for what they choose.
Oh, and my DD friend who just competed Nationals as a barely 12 year old L9 never scored 36+ in any compulsory level OR L8....came close repeatedly. And my DD has quite a few 36+ scores under her belt, lots of state medals, and still really wasn't ready to move up. Each kid has their own path to follow.