TOEI Animation has admitted ripping off music to use for the score of DragonBall Kai and stated they will be replacing all the music in the near future. Here is a direct translated quote:
The existence of multiple suspicious musical pieces which may infringe on the rights of third parties has been confirmed within the musical compositions recorded for “Dragon Ball Kai”, an animated television work produced by this firm. The relevant musical pieces are used as background music in “Dragon Ball Kai”, and measures are promptly being taken to replace the relevant musical pieces from the background music of “Dragon Ball Kai”.
Also, we are proceeding with a swift investigation of the facts, and discussion of countermeasures with concerned parties in the near future.
TOEI has also listed Shunsuke Kikuchi as staff under the DB Kai section, whom composed the original score for Dragon Ball Z. So, they will now be replacing all current music in Kai with the original score, so it is also possible that FUNimation will do the same or even revert back to work from Bruce Faulconer.
This recent copyright infringement on behalf of DB Kai could also be the reason why they did not continue Kai towards the Buu saga and ended it at Cell.
Nonetheless, this also means TOEI will most likely be removing all DragonBall Kai products off the shelves for the time being until they get everything replaced.
And if you are curious as to what tracks were ripped off, here's a few that DB Kai got "inspiration" from: Terminator: Salvation theme and Avatar theme.