If anyone's interested, i have a full (as of MPT 1.17.053) list of the hardcoded strings that i was planning on basing a localized string file from. Jojo of course, has added new features and dialogs, so it's not complete, but it'll take away about 80% of the work of looking for all those strings.
But like Jojo said, you'll hafta go in and alter the code to get MPT to access an external file for its text strings.