I tried Front End Friend. I know it's just getting started, but so far, it looks pretty promising! I like the simplicity.
Once set the paths and I imported the favorites, I launched it. I was able to scroll through my list no problem. I did not launch a game. Instead, I realized I wanted to re-path to a different set of screenshots. At this point, I couldn't remember the command-key to bring up the prefs, so I command-Q to quit. Then, every time I have launched it, I get the launch screen with my list but keys do nothing and all I get are alert beeps when I press keys. I am going to trash that file as your website suggests and start over.
I could not get it to allow me to change keys. Actually, when I looked for SPACE, or UP DOWN LEFT RIGHT arrows, they were not in the list. These are going to be pretty common choices for a front end so folks can use their Player 1 joystick to navigate.
Anyway, I look forward to the enhancements you are planning! Way to go!