At least on the invisible invader, it's not allowing a second attack ever from the app unless you move of the square. Never mentioned attacking too fast, just can't attack again.
Couple things noted hunting on the app.
-Unable to see super elites creatures on the list if there are more than 5 creatures in a square. SE shows up off the screen and you have to scroll. Event creatures still shown first.
-Unable to purchase buffs from but market using banked gold. Required to withdraw first.
-Killing said SE causes the game to freeze requiring it to be restart to correct. Still register the kill.