The developer, Maupro12321, very kindly shared the source code:
https://github.com/ObscureMosquito/MapsX/blob/main/Tweak.x
Instead of porting this to SIMBL I tried modifying Squid's configuration to do a simple URL rewrite:
$_ =~ s/^(https?:\/\/)gspe(\d*)\.ls\.apple\.com/$1gspe$2-ssl.ls.apple.com/g;
The URL rewrite seemed to be working, but it didn't fix MapKit, which actually appears to have already been using the
-ssl
domain. You can see the problem right in the system console, the url it tries to access returns 503.
If anyone wants to install CharlesProxy/MitmProxy on a newer and older Mac and look at the URLs being called, maybe we could investigate further. I just don't care that much about 2013-era Apple Maps. There's a reason everyone panned this thing when it came out, sure it got better over time but this is the early one.