Alright. I'll mess up with it until I find a satisfying setup ^^
I would suggest to add to LEDBlinky a special "expert" mode where the only logic is given by the LEDBlinkyControls.xml file, so it'll completely override this "start and coin" weird logic where sometime I get veeery strange behaviors.
For exemple, in 4 players games with no Start Buttons (only 4 coins) like TMNT, Gauntlet or Sunset Riders, i managed to get the voice announce the 4 coin buttons ok by tricking the software.
I setup fake START1, START2, START3, START4 buttons in the Controls Editor, with a 0,0,0 color, and a dummy text. If I don't do that, the program WILL speak non-sense and announce ghosts Start Buttons.
Anyway, now it kinda works, but for a mysterious reason, one of the 4 Coin buttons... will not lit. Tried for hours to fix it, but didn't succeed.