I think the issue is probably on the other side actually. Energy champs are supposed to be gated by pool size. They have a resource pool that can't be increased, but also can't run out over a long term. In lane this lets them use more spells but not go oom, but in team fights they are restricted (in theory/they should be if designed well) to saving their energy bc if they use too much on single spells during poke fights, they won't have a large enough energy pool for a full combo during a real engage.
Mana champs in contrast should ideally be forced to play conservative with spells early and then can build up a large mana pool so in a consolidated team fight that drags out the mana champs will be able to cast more rotations of spells in sequence bc they don't use as large a % of the resource pool.
If this isn't happening bc energy champs can spam their spells as fast as mana champs in team fights and not run out of energy then mana champs have too long a cd which keeps them from competing, or energy champs have too low an energy cost. However, neither of these is the same as energy/mana less champs having too short a cd. Non energy champs need longer cd spells (or weaker spells, or ones that have to work together, or whatever they need to give up for balance) bc they don't cost anything but cd (unless they are health based in which case short cd is okay again), but energy champs need short cd spells so they can be balanced around running out of energy in all ins if the champ is played poorly. Longer cd just makes managing energy in fights easier for bad player, nerd the energy numbers if anything.