To at least answer your question, she got the ability to airdash cancel j.S, j.H, and j.D much later during Accent Core. There's some info on norematch.com (which has some old X2 vids, but more importantly, info about Millia in general and things between editions).
If that's all you're able to get right now then you're right, it's better than nothing. But I encourage that you pick up a newer edition.