So I probably spent way too much time researching this -
I’ve tried to track these down from the Core listing - Calexit (2017-2019) - #4 and 5. They don’t seem to exist. I’ve yet to see a listing anywhere on eBay (your link doesn’t lead to any) or any of the major online retailers like Midtown or Mycomicshop where they would at least have a placeholder even if not in site. These issues have the same release date listed here, we know that would have been updated by someone at this point if someone had them.
The cover for #4 in the Core info is actually variant 1D for Calexit Battle of Universal City (2023-2026) so it probably never went to print and they repurposed the art for the cover. I have yet to see the art for #5 anywhere.
There are also reddit conversations about the series being canceled and ppl did not know where 4 was being released. If you want the link for those I can supply them but that seemed like overkill.
If anyone else can confirm who might know either way, please feel free to chime in. Otherwise I’m pretty sure they were cancelled.