Glad you got it working.
FBA for NEO-GEO is really great on the PI 3
I am going to include how I got FBA working for me since choosing to use mame vs fba is better than feeling like you have to due to FBA config issues.
My system is configured for my arcade cabinet with an I-Pac2 - so keyboard setup.
Final Burn Alpha was a pain in the butt to configure the controls, but, once I did, I was very happy.
I really wanted to run as many of the metal slug games as possible. With FBA you can run 1-5 + X full speed with no glitches. I could not do that with the current Pi Mame's.
I did 2 things.
1) turn off save settings on exit in the main retroarch config (/opt/retropie/configs/all/retroarch.cfg).
config_save_on_exit = "false"
2) Create a custom retroarch config for FBA that was based around the capcom fighter controls, then create custom config files for the neo-geo controls per rom name. The per rom name configs live in the rom directory, not the config directory. /home/pi/RetroPie/roms/fba/ directory
Example below: (Just using romname + .cfg on the end)
mslug.zip.cfg
# Settings made here will only override settings in the global retroarch.cfg if placed above the #include line
input_player1_a = "shift"
input_player1_b = "x"
input_player1_y = "c"
input_player1_x = "v"
input_player2_a = "k"
input_player2_b = "i"
input_player2_y = "j"
input_player2_x = "l"
#include "/opt/retropie/configs/all/retroarch.cfg"
I repeated this for all the mslug games - (mslug2.zip.cfg etc...)
Here is my main retroarch config for FBA as well.. just in case you want it for reference. (/opt/retropie/configs/fba/retroarch.cfg)
Again, my main file was set up for the Capcom fighters and also has enabling the shader for horizontal scanlines.
# Settings made here will only override settings in the global retroarch.cfg if placed above the #include line
input_remapping_directory = "/opt/retropie/configs/fba/"
input_player1_a = "x"
input_player1_b = "shift"
input_player1_y = "alt"
input_player1_x = "space"
input_player1_start = "num1"
input_player1_select = "num5"
input_player1_l = "ctrl"
input_player1_r = "c"
input_player1_left = "left"
input_player1_right = "right"
input_player1_up = "up"
input_player1_down = "down"
input_player1_l2 = "enter"
input_player1_r2 = "v"
input_player2_a = k
input_player2_b = i
input_player2_y = a
input_player2_x = q
input_player2_l = s
input_player2_r = j
input_player2_up = r
input_player2_left = d
input_player2_right = g
input_player2_down = f
input_player2_start = "num2"
input_player2_select = "num6"
input_enable_hotkey = "6"
input_exit_emulator = "escape"
input_pause_toggle = p
video_shader_enable = "true"
video_shader = "/opt/retropie/emulators/retroarch/shader/crt-pi.glslp"
#include "/opt/retropie/configs/all/retroarch.cfg"
Of course your keys will be different, but this is a good example of how to config controls for FBA and then individual rom configs.
Setti