I’m not sure if this solves your problem, but here is a way that I tackled this task…
I used Time Warp (not Audio Warp) to align the timeline to my audio track instead of aligning my audio track to the timeline (do not use the musical events follow version of Warp Tool). The audio track was not perfectly quantized, but all other tracks were in sync with the drum track. This created multiple tempo change points in the tempo track based on the drum track, but they were all very small fraction of a BPM differences. Point is, timeline was warped to match the drum audio track.
Then I selected all audio events and used Audio > Advanced > Set Definition from Tempo. Now the audio warp maps in all audio events on all tracks are aligned to the project grid which is aligned to the drum track. I make sure all audio events are all in musical mode and delete the tempo track automation points. All audio events warp automatically to the now-fixed tempo. I can change tempo freely and because of musical mode all audio follows it automatically.
I think this only works in Cubase Pro though because that’s the only version with the Time Warp tool.