Wind Tower in Coop (Possible Solution)
As a guest, I had successfully done this thrice with random people.
From my past experience of solving this lag issue, both players need to stay on their note for around at least 2 sec before moving away, because in my observation, it seems that this puzzle doesn’t care about how much longer a note is played, but does get affected by how short a note is played.
I also used gunshots to facilitate the synchronization. One gunshot means it’s time for both players to get on the note; after staying on the note for at least 2 sec, then 2 consecutive gunshots are fired, meaning it’s time for the players to get off of the current note and get into position for the next one.
Of course, this pattern (1 gunshot to get on, then staying, and finally 2 gunshots to leave for the next note) has to be repeatedly performed several times by the party leader to the partner in order for him/her to understand the message of “keep staying on the note till 2 consecutive gunshots are fired.”
Also, although unproven, it’s a hypothesis that the solo-able puzzle (Wind Hollow Circlet ring) has to be solved before the coop puzzle (Band Band ring) can be started. Because my first time doing this as a guest with randoms, we skipped doing the solo-able puzzle (Wind Hollow Circlet ring) and went straight for the coop puzzle (Band Band ring). However, we could not get the green/blue wind to appear (the visual sign of successfully solving a puzzle) for the coop puzzle, until we solved the solo-able puzzle first.
In the 2nd and the 3rd time as a guest with randoms, I didn’t test this hypothesis of the order of solving the two puzzles, because it’s very difficult to get random people to be patient with the teaching of the gunshots pattern without firstly giving them some incentive (Wind Hollow Circlet ring); thus the solo-able puzzle got solved first, and I got no chance of disproving the hypothesis that the order of puzzles matters, which can be easily disproved by successfully solving the coop puzzle first, and then the solo-able puzzle last in order to show that the order of solving the two puzzles does not matter.
In my experience, the sparkles showing up at all indicated a successful playing of the note and you can move to the next. The trouble I had was the timing of the final note, which seemed to require moving on to it quickly.
Anyway, for me it definitely did not seem like there was any reason to stay on a note once the sparkles appear.