A Document's Fonts collection holds references to all fonts used in any document. Create a simple text list of your font database, containing the full name, and, if possibly required, the font version. This ought to be faster than connecting to the database and querying it per font -- simply copy the full list into your script. Then have the script compare each document font against the list.
If you also put a list of your legacy document filenames into the script, it's even possible to have it open, examine, and close, one by one.