I wouldn't personally use a wait action at event 15. I learned the hard way that in this circumstance, a timer is generally superior.
Place a timer behavior on your player object.
replace the condition at event 15 by "Attack1count = 0" (instead of <= 1)
replace "add 1 to attackcount" by "set attackcount to 1"
replace the wait action by "start timer for 0.25 seconds"
delete subtract 1 from attackcount
add event :
Player object, On timer --> set Attack1Count to 0
add condition : Keyboard > on A pressed
add action : set Attackcount to 2
Depending if you want to allow the player to spam attack1 after combo1, you may want to add "start timer for 0.25 seconds" (or a different value) at event 17, so that attack 1 couldn't be launched before 0.25 second.
I don't know if it's clear, I didn't tried it in the editor and I'm not 100% sure that I understand what you want to achieve, but hopefully it'll help.