i think a repeat loop will run over and over and not stop with a timed event.. so you wont see a flash until the last loop.
I would make an actor block, attach to that actor that you can call, that has a timer event in it, that does the flashing for you, and call it once.
So i would create an Actor block that has a do every section in it, and pass in a number (time) to flash for
So the actor flashes using its only behaviour..
Maybe have a behaviour that is disabled, and activate that behaviour when you need it to flash, then disable the behaviour when you want it to stop. Something along those lines..