I'll just explain. First of all, you can not have any more than 1 single mesh with the same name, so you can't have two bonnet_L0s etc.
ELS uses extras 1-9 to spawn and despawn to imitate flashing emergency lights. They have to be setup like this:
extra_1 (this is just a dummy)
- extra_1_L0
- extra_1_L1
You follow that patter for extras 1, 2, 3, 4, 7, and 8.
However 5, 6, and 9 are different.
extra_5 (this is just a dummy)
- extra5_L0
- extra5_L1
For whatever reason the game needs the first underscore to be removed.
So make sure all of the lights you want to flash at the same time are attached to one single object and named properly.