The database is pretty straightforward to update and create your own. I maintain a DB down this part of the world (South Pacific) with all the local and regular international visitors in it.
Pretty much all you need is the ICAO code and the aircraft type for the DB to show up the correct icon (or closest approximation), I have also added other fields to mine which you can modify the code to read as well (Owner, Aircraft type description etc).
There is a Python script that converts a correctly formatted CSV file to the JSON DB, default CSV format looks like this (the desc field is not used in the vanilla FA code though):
3A21ED,F-OIPN,AT76,ATR-GIE ATR 72-212A
Here is a link to the Python Script:
I run this on my desktop and copy the JSON DB over to my PI, syntax is:
python csv-to-json.py vrs.csv db
Where vrs.csv is the CSV file as formatted above and DB is the output directory. You should have an empty directory for the output. You should also delete all the json files out of the DB directory on the Pi before copying in the new one. To test you will need to clear the cache on your browser first or start a new private session.
Also if you are really brave I have compiled a whole pile of extra icons for many aircraft types, it is sort of ported to 3.5.0 with some caveats, thread on that here (might want to jump to end as most of the screenshots are now dead thanks to DropBox changing their rules):
If you have a good DB my markers.js is pretty much a drop in and replace.