The cameo I was mentioning was "This Little Piggy". She had maybe 5 lines in the whole thing, definately not a major role. Also, if there were 11 years between her episode and JLU, then she would have looked a good deal older. she didn't, and neither did Batman (although his new art style helps hide any aging). Besides, she learned her magic from her Dad, and I'm pretty sure he's dead by the time she appears in Batman.
Also, 11 years seems like a long time. Batman in B:TAS has, at the beginning of the series, been batman for 7-9 years, since Dick was robin at age 12 and he's 18 when he first appears. Bruce needed years to become a master detective after he went off to train as a teenager, plus probably atleast one solo year, so lets say he was 23 when Robin joined him. That would make him 30-31 during the beginning of batman: TAS, which I think works. If JL happened 11 years after that, he'd be in his forties, and that seems a bit old for him in JL. I could be totally wrong, but thats just how I worked it out in my head.