The bombers were they to train with the carriers. Timing may look like they were there as response to Chinese flights from a day before but I think the B-52H flights are more planned. Now the Chinese record flights (38 and 39), I think is in response to the 3 carriers assembled. Taiwan just happens to be around the area. But of course, it will take credit for all that attention.
Another way to look at this is US (and UK) assembling 3 CSG is because it sees China as its main threat and is conducting exercises to familiarize units.
And China flying record flights from different squadrons in coordination is because its sees US as its main threat/rival and will use this chance to provide good background exercises for its forces.