On watchOS 7 and shareable watch face - an edge case example (hit link for the details)

What if a watch face uses a complication from a third-party app that the other user don’t have installed? How would this situation be handled? Highly probable edge case IMHO.

watchOS 7 to include new ‘International’ Apple Watch face with multiple country flags - 9to5Mac 9to5mac.com/2020/03/1…