Leaping is different from leaving, in that by the time you're jumping, the spell has already completed, it's not like you'd jump, intersect the ward, fail the RR and long door back to your original starting location. I don't think the destination of the leap is relevant the way the leaving destination is.
To offer a 5th example. . .what if you cast invisibility on yourself, walked out, then walked back in?
Per the change, #5 would provoke an RR, while per the original, it wouldn't.
Part of the logic of the "cast across" is the active magic crossing the line in the outside-in direction. . .and "Cast" implies the RR needs to be resolved immediately after the spell casting roll, not that the ward has an ips post facto effect on magic previously cast.
Otherwise you could make a ward vs Weapon I spell, and dispel magic items entering the radius, while the intent here would seem to be preventing you from casting Weapon I from outside the radius on an item inside it. . .if that makes sense.
I'd say that any situation in which the spell being cast crosses the radius after spell casting is resolved, and before spell effect starts, are the ones it applies to.
It's an odd wording, that spell.