Oh I guess you do have a point but I stumbled upon the solution accidentaly. When I got the spell itself and I tried to use it, it just wouldnt do anything, my reaction was like "wtf is this supposed to do". I googled it and I found out that it was only useful in the last boss.
I figured it out when I tried using Chrono Cross (in the Dario fight of all places), realized the connection between those chimes, spheres in the corner of the screen, and the
Seventh Element, and applied video game logic to realize that I needed a correct sequence. Then I got to that room in Terra Tower, recognized the chimes and recorded the order down.
Then I got to the final boss fight, noticed the lack of sound, and realized that at a certain point, the boss flips out and starts using the sequence itself (before that point the boss just spams Green and maybe Blue or Yellow elements at you and has zero physical attacks at all; and after that he just stands there until you beat him the right way or the wrong way, provided you survived the spam since it's out of spells at that point).
The tl;dr is that the Time Devourer is a pretty lame final boss. The other Time Devourer is pretty much the true final boss.