Hi , trying to animate spherical movements (like rotating a directional light or a camera) without linear quaternion is an absolute nightmare, as you can end up with unexpected behaviors: depending on the angles you are working when you rotate on an axis another one will move as well. It turns something that should be done in seconds a chore that can take a lot of time and at the end it won’t look as good for the trained eye.
In our project we work a lot animating directional lights and cameras through sequencer, and so far the only solution is to keep working with Matinee for this elements, as we can use quaternions there. I think Sequencer should have this crucial option if matinee is supposed to be deprecated.