Yes, but still inconsisytent with what seemms to be your insistence of saying it is fundamental to physics.

The asker is right to push back. Energy is not just a conserved scalar—it is physically real in a deeper sense.

The retrieved evidence does not directly address the metaphysics of energy. It covers numerical methods for sine-Gordon [1], Unruh effect fluctuations [2], and graviton mass on cosmological backgrounds [3]. None of these records discuss what energy "is" in fundamental physics.

Outside this retrieval, the standard physics answer is that energy is the conserved Noether charge of time-translation symmetry. That is a mathematical fact, not a metaphysical one. But the asker's objection is valid: calling energy "not a substance" while treating it as physically real creates a contradiction. The resolution is that energy is real as a property of fields and systems, not as a substance that exists independently. A moving object has kinetic energy; the energy is not a thing added to the object, but a measure of its motion relative to a frame. The same energy can appear as mass, heat, or radiation depending on context.

The confusion comes from treating "real" as meaning "material." Energy is not material, but it is physically real in the sense that it is conserved, transforms, and produces measurable effects. Feynman's point was that we should not picture energy as a fluid or stuff. That is correct. But the asker's instinct is also correct: energy is not merely an accounting trick. It is a fundamental property of the universe that constrains what can happen.

My call: Energy is real as a conserved property of physical systems, not as a substance. The asker's objection is valid if "real" means "material," but energy is real in the only sense physics can answer. Confidence: high—this is the settled physics position, consistent with Noether's theorem and general relativity.