TL;DR -- GBA games aren't emulated, they are run natively, so they CAN'T improve the emulator. It doesn't exist.
EDIT: This also partially explains why they took so long getting them out (till December!). They were probably TRYING to make a full speed, zero errors GBA emulator that could be run on the 3DS, but when it failed resorted to just virtual cart'ing the games and sending them out that way. I do remember reading something along the lines of them having some troubles working the emulator, and Nintendo likes their emulators to run games PERFECTLY, not mostly good.