Gymnastics is a long term process that will be filled with peaks and valleys, so don't worry too much about the timing. I think it's good that you had a conversation with the coaches and hopefully they gave you some specific areas for your daughter to work on -- goals of sort.
My DD had a similar experience when she was on pre-team (the old L2). After 4 months, all but two girls (including DD) were moved to L3. My daughter was very upset because she thought she was better than some of the other girls. I spoke with the coach and she told me that they debated whether DD was ready. They thought she was close and that she may be ready in a couple months if she had a few privates. True to their word, they moved her up after a couple months to old L3 (which was a competition level at that gym). Fast forward to today, DD is at least 2 levels ahead of every one of those girls who moved up "early". Many of those girls aren't even in the sport any more. That incident was a motivator in many ways and made DD want to work harder to prove them wrong.
Coaches are human and I understand why they made the decision they did way back then. Just make sure your daughter understands what she needs to do and tell her to take it as a goal to achieve rather than an obstacle to overcome. Oh, and running is pretty important -- especially for vault. They judge the run in new L3 and the power and timing are important for higher level vaults.