I'm thinking it's a case of sound files simply not being updated. Prior to the update where the pull function was introduced, return to gate wasn't an option, so the entire callout was tied into we_have_good_engine_start.wav. Now, there's a separate sound file called cockpit_to_ground.wav since there are new callouts for if one wishes to return to the gate, but if the first sound file didn't get updated, that's why. If I remember correctly, if you go into the Add-on Manager folder, go to \couatl\GSX\sounds\pushback, then there's folders 1, 2, and 3. There is a we_have_good_engine_start.wav in all three of those, and I don't know if those got updated.