The dance boots aren't a problem. Freestyle boots seem to be getting lower and lower, and someone very reputable told me that Jason Brown uses dance boots (dunno which model). Some dance boots are crazy stiff, but jumping will break any boot down faster.
Back in the figures days (which helped develop ankle strength) our boots were less stiff then they are today. Just sayin'.
Re: blades. For jumps the toepick is key. I'm not familiar with the apex, and can't really assess the toepick from the photo on Ultima's site. Honestly, I wouldn't trust that pick profile at all for jumps, despite it looking more aggressive than the pick on the Wilson Dance. The drag (bottom most) pick is necessary for most jump take offs (even a waltz needs that drag pick) and she'll have compromised grip for landings. I don't know anything about how the slimline would react to the stress of jumps. It probably wouldn't be an issue for singles, but I wouldn't care to test it.
If it were more entry level dance blade (akin to the Coronation dance, or the Ultima synchro) with a proper toepick, she'd be fine. The reduced drag picks force a greater knee bend on jump entries- not a bad thing. Fwiw-I do jump on my CorDance's, but I don't have even my lutz anymore, let alone any doubles. If the opportunity presented itself to start jumping again, I wouldn't hesitate, and would keep my current blades.