Editing color curves at the emitter level will not propagate to the system level when saving and applying. The curve will look correct int the system stack, but the particle colors will not match.
The system color curve will be updated, but the particles will not match.
The particle colors may update correctly the first time the change is made, but afterwards will not update correctly.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-74196 in the post.