Why would you still use that thing.
You don't need to 'import samples' with Mida2GBA or Sappy at all unless you want to. As long as you point it at the instrument map it will use the FE7 instrument corresponding with the MIDI setting. After setting up the MIDI (7 tracks/samples, all the fun stuff covered elsewhere), running it through MIDI2GBA and inserting it with Sappy takes all of five seconds.
For the love of cheese, Brendor, you need to kick this habit of talking about stuff without fully understanding it.