I don't think Olympus Coliseum is taking place after the events of the movie. Yes, the majority of Olympus' plot in previous games is original due to the inclusion of Final Fantasy characters like Zack (BBS), Cloud, and Auron (KH2), but it still takes place during the events of the movie. I mean Birth By Sleep has a young Hercules training with Phil even though it is at the Coliseum and not in Phil Island from the film and the Olympus plot in Kingdom Hearts and especially Kingdom Hearts II is taking place during the middle of the movie and introduced more characters from the film such as Megara, Pegasus, and the Hydra. And while the plot is original it did draw some references scenes from the film such as the Hydra attacking Hercules and Hercules saving Megara even though it's done in a different fashion.
Now that Disney including Walt Disney Animation is involved with the Disney worlds, from what the latest scenes we've seen for the plot on Olympus, yes part of the world is original as Sora is coming to this world to train with Hercules to get his powers after what happened in Dream Drop Distance but it's still taking place during the climax of the movie when Hades frees the Titans from their prison and launch their attack on Mt. Olympus.
Lastly, the Ice Titan that Hades summoned in BBS to battle Aqua, was not the real Ice Titan, but a proxy weak version called the Ice Colossus.
Now that Disney including Walt Disney Animation is involved with the Disney worlds, from what the latest scenes we've seen for the plot on Olympus, yes part of the world is original as Sora is coming to this world to train with Hercules to get his powers after what happened in Dream Drop Distance but it's still taking place during the climax of the movie when Hades frees the Titans from their prison and launch their attack on Mt. Olympus.
Lastly, the Ice Titan that Hades summoned in BBS to battle Aqua, was not the real Ice Titan, but a proxy weak version called the Ice Colossus.