Can TapTap Hotkey Extender be used to simulate three simultaneous keystrokes
not sure what you are asking -- taptap can't detect a triple tap, only double taps (though this is possibly something that could be added); but it should be able to simulate combinations of 3 or more keys when triggered.
regarding taptap solution vs autohotkey solution, ahk is an incredibly powerful and versatile tool that can do tons of things.
wheras taptap was designed with one thing in mind, detecting these kinds of tapping keypresses as efficiently as possible with smallest impact on cpu and memory and resources.
this is something to care about because these are keypresses that are happening constantly as you type, and you don't want it slowing down your pc.
while i can't say definitively that taptap works more efficiently for this task, that would be my strong suspicion and i'd love to see some benchmarks comparing the two approaches. though in truth it may be that the impact is minimal, when doing anything but heavy keyboard pounding, if even then.