I think introducing Ororo in BP2 just makes sense(though I would make her more a contemporary of Shuri in terms of age, and not a romantic interest for T'Challa). No one is mad that T'Challa was introduced first in CA3. He got an excellent featured supporting role there(I actually like T'Challa more there than in his own solo where the women of Wakanda and Killmonger actually overshadow him), and then went on to have his own blockbuster movie. While I definitely want the first MCU team X-Men movie to follow the Giant Sized X-Men model, including Xavier recruiting goddess Ororo, I think having a featured cameo of Ororo in Kenya, which is just across Lake Victoria from Wakanda in some maps, in BP2 is just a logical cross-promotion. I definitely want a Storm solo film, but there's nothing wrong with using the shared universe of the MCU to it's fullest advantage, and BP1 did an amazing job with the female characters featured therein, so why not one more?