I'm a bit busy with work now, and don't have time to dig in to the file
contents myself.
aprs.fi takes the kml= URL and simply gives it to the
Google Maps API, Google's code takes care of
downloading/decoding/Displaying the KML.
If there's some KML that does display and something that doesn't, you'll
probably want to try to identify the exact differences in the KML files
and then try to mix and match to see what works and what does not work.
With some luck, Google Maps API code might also print out some decoding
errors or such in the Javascript console in your web browser.
- Hessu