On the surface level, it's a pretty good choice to introduce the idea of going beyond Marvel into other media properties insofar as that is possible - DC being another comics company makes it a safe bet for a reference readers will get, with the Source Wall being a particularly good choice with its general iconicity and place in adaptations like the DCAU.
But the Cosmic Raptor is anything but, to be frank it seems like one of the worst choices of cosmic DC figures. It's at a precise point in regards to time wherein it's too recent to be an established icon but too old to be in the zeitgeist, plus it's a pretty minor part of the run it's from so even people who've read Synder/Tynion JL might miss it, although maybe that helps with copyright or something like that. Also it's not from the DC multiverse, it's from an omniverse beyond, which is fitting for the Storm storyline but unhelpful for showing this is part of the DC universe (although it would be very funny move to reveal this is another multiverse in the DC omniverse). Behaviourally it also seems off, though we don't have much to judge by - the DC raptor was well spoken and legalistic, presumably to give a clear impression of a cosmic judge. The Storm Raptor has one line, "Rot in primordial ooze, shit stains". I guess you could argue its a different Raptor, but it's drawn very similarly to the DC raptor (the Storm Raptor seems much brighter and smallerthan the DC one but the size is just practical and the lights could be argued as just lighting, there is only a single panel of the DC raptor to work with) and it's a very pronounced difference. I get the feeling it's written that way just for the "definitely not Jean" bit but her mistaking the Raptor for Jean doesn't really work when the Raptor is monochrome with a coloured glow and the Phoenix is almost always incredibly bright. If Storm was confused it would be one thing, but she greets the Raptor eagerly. Also the raptor doesn't seem to be aggressive in DC, it seals away Perpetua but that's because she's super evil. I presume it's meant to be attacking in order to put Storm and her not-mom into the source wall, but again it only did that to Perpetua because she's super evil. Plus that motive falls flat when it just flies away after they fall in the primordial ooze.
I know this is all pretty nitpicky, but with this sort of reference I feel like the details are really all you've got. Until #4 came out I was genuinely kind of uncertain whether this was even meant to be the DC Raptor whether this was even meant to be the DC Raptor when it was behaving unrecognisably. And in truth it feels like a missed opportunity for a more pointed reference - I know more iconic characters would probably pose a bigger threat copyright wise, but there's definitely ways to allude to others. Off the top of my head, the chase framework is perfect for an omega beams segment, which could surely be done in a recognisable but permissible way (I can't imagine DC lays claim to "red beams that chase you" but 99% of readers would get it instantly). Just the weirdest choice.