They also aren’t in the Energy checklist of @credits , who collects Energies, so I’m pretty sure they indeed do not exist. But perhaps @credits himself can shed some additional light on the matter?
I’m pretty sure the reason why the Metal and Darkness Energies does have Reverse Holos is because they were Rares in the Expedition Base Set, while the other Energies were just Energies. (I always counted Energies as below Commons when there is no rarity symbol present, but most modern Energy cards have Common symbols now, so I guess Energies can be called Commons as well.)
Greetz,
Quuador