Well,I am aware of the warning(prohibition?) against taking "energy" to be a "thing" rather than a property of a system and am now reminded of the importance of keeping in mind that all we have is models.It doesnít override, itís just not related to speed of propagation at all.Not only useful but essential. All energy measurement depends on motion and/or position of the observer.So does that kind of override our (my) intuitive difficulty in accepting the experimentally verified fact that the speed of em propagation does not depend on the motion of the observer?It seems to me that the two processes are linked...No, it is just part of the way we measure relative energies.
Letís say you are driving along and a car comes up behind and hits you, travelling at twice your speed. Compare the relative kinetic energy of impact to the case where the other car is travelling only slightly faster than you - nowhere near as much kinetic energy transferred nor damage done.
Kinetic energy is relative even at non relativistic speeds. Light is no different except that because itís speed relative to us is always c and itís rest mass is zero, we need to use its measured momentum which it was discovered is related to its frequency.
I notice you are trying to make sense of some of the more esoteric terminology bandied around, but reread and take to heart @alan comment about ďa photon being modelled as ...Ē because it is easy to be led down rabbit holes.
Can I ask ,then if we can model the propagation of light in terms of the propagation of energy through a system?
Say the Sun explodes,could the energy distribution** in the Solar system be modeled as propagating from one region to other regions ?
The speed of this propagation would be limited at c in a vacuum ,wouldn't it?
** does that term ""energy distribution" have a meaning or is it word salad (googling it ,all I find is Energy Distribution Companies and perhaps a few uses in physics that I don't think I had in mind)