I tested on my MISTER/FPGA with the ps/4 joypad in usb which works with the games which are in two botton mode with success
Smartbomb is assignable in settings. Is it button 2 + any keyboard assign. Or one of the keyboard assigns *is* button 2?
You can use either button 2 on a GS64 compatible joystick, or press the assigned key. Alternatively, just use auto-smart bomb which will auto-trigger if your ship gets hit by an enemy or a bullet.
Thanks! Love it, but you know that already....♥️