Since your trip is in April don't overthink about the aircraft type at this point, I believe you will simply lose track of how many times they will change the type between now and April.

I don't know if there are any flying at the moment but I don't think CX is planning to move away from having regional J for some of the A330. Those moving (back) from KA will have regional J for example and they will need those capacity for short haul when the demand is picking up again.

They love to play with different type of aircraft assigned to the flight until boarding at gate even before the pandemic so just wait until March or so to start worry about that