Scenes in HA are essentially dumbed-down scripts. They can have the same end result but with fewer options, and don’t even have a state, so once you enable a scene you have no idea if it’s active or not. Contrast with Apple Home where you can create a scene and if all the accessories happen to match the scene target, its state shows “on”.
Basically while both systems use the term “scene” they each have a very different idea of what that word should mean.
Personally, I think HA needs to fix this underlying problem to make scenes stateful before they can be detected correctly by Apple. The author of stateful_scenes in HACS has done some great work along this track. If this FR fixes that, then you have my vote.
Edited to add: another sticking point is that, for full compatibility you likely need to ensure every entity the scene controls is exported by HomeKit Bridge. So either the Bridge should throw a warning/error if you forgot to export a scene’s accessory, or the Bridge should automatically include all the scene’s entities as if the scene was an include_entity_globs filter entry. I posted another FR to improve the way filters are defined.