I’d be more surprised if there had been any significant contact between the two couples. The birth of a new baby doesn’t make everything that’s come before any less hurtful. Harry may have texted pictures of the baby or something along that line but as far as an actual family conversation via zoom or FaceTime.. things may be too raw for that yet.
Based on everything he and Meghan have said over the past couple of years, I don’t think Harry has been close to William, Catherine and their children since well before he and Meghan left the UK. I doubt the Cambridges have seen Archie more than a handful of times, let alone Lili.
I’m sure Catherine, in particular, would love for the Cambridge kids to have the same sort of close relationship with Archie and Lili as they’ll likely have with Pippa’s children, (and the geographical distance alone wouldn’t rule out the cousins getting to know each other well). I think if you’d asked her five years ago what things would be like when Harry had children she would have expected that she and William would have the same sort of affectionate relationship with their niece or nephew as Harry then seemed to have with George and Charlotte. It’s sad things don’t seem to be heading down that road, especially for the children.