Wow... I am so shocked and happy to see that this project exists. I could go on for hours about this. :)
I only have played the very beginning as of now, and noticed that the title screen still has Charizard's cry even though Charmander is on the title. (I was impressed to see Nidorino with the correct cry during Oak's intro) So I was just wondering if you were planning on changing the title screen cry, or maybe just use Charizard's sprite for consistency? small concern, it was just awkward to start things up and see that. (And considering the ludicrous amount of work you've put into this, I feel like this was just a small crumb that didn't get noticed lol)
The other thing I was just wondering about was if you were going to ever include the option to play as the girl, since this is a fire red and leaf green-based decomp. I know Red and Blue didn't have the choice of playing as a girl, so maybe that is why you removed it.
Lastly, I know you've mentioned replacing the audio, and was wondering if you have tried using that GB Player feature from other hacks like Fire Red Throwback to get the awesome 8-bit tunes into the game. The only downside I noticed with the GB Player, is that Pokémon cries and sound effects get very drowned out and overpowered by the 8-bit tunes to the point where you can only hear the music and not much else. Maybe you will be able to do it better. :)