Yea, it's really weird.
The second one is even weirder than the first as he's literally above me and I still stuff the Superman with the D4.
In that second one, did you start the superman right there, or was it from farther out? In the first one Raiden's probably just getting stuffed in his start up frames. It's annoying because you'd expect the move to clear the ground fast enough, but it sort of makes sense that you get knocked out of it.
You might be showing it in the second, I can't tell, but Raiden can actually start his superman outside of d4 range, like at full or midscreen, and Raiden will still get knocked out of superman. It's really annoying, since in most cases Raiden would win in that situation. Sometimes she'll just be using d4 carelessly and I'll try to whiff punish with superman, but I'll be too slow and get hit by a 2nd d4 she just mashed out.
The other thing is that once in a while if the d4 doesn't beat superman, the superman will go right over her. I've never been able to replicate it intentionally, but I've had it happen to me a couple time during matches.