Light years beyond, thanks!
Can you now deal with a key_timer as combos are time sensitive? Also, the remaining questions are - two keys at once. And charging a single key for a time before moving to the next key.
Two keys is an assumption as the engine checks each frame and one at a time, again needing a timer and lastpressed check.
You're Still, a Master and this is AUM worthy - Hail @txesmi.