Vault has always been her weakest event. She doesn't like committing to falling flat (the L4 vault). She gets up into the handstand but then tends to walk on her hands and collapse rather than fall over backwards. She hasn't really tried the L5 handspring vault much but the few times she's gotten to try it, she's really liked it, much better than falling flat (there's video of her first attempts on our youtube channel). I actually think the L5 vault is going to be much easier for her than the L4 vault.
Actually, the vaults are not all that different between L2 and L4. For AAU it is the same vault just progressively higher. At L2 they vaulted onto 3 stacked mats, 4 mats for L3 and then over the vault table onto stacked mats for L4.
And you're right. DD's all about learning new and harder skills. That's her favorite part of gymnastics, even better than winning medals! She told me last night that she's going to do a giant at practice today! I told her she really should wait for her coach to help her with that and not to try doing it on her own.
I'll bet your little one is so very excited, especially if you've got an older daughter at L4, too. Does the little one really look up to big sis and want to do everything she does?