Hiryu Kaen would have probably done more damage than all the other shallow attacks but it would still fail to scar Kaido.
The reason why I say more than the other attacks is because there was an emphasis placed on Zoro putting so much CoA into that attack that even he couldn't control it and was left to miss and huff afterward. Big Mom's reaction also makes the attack stand out.
After that miss, he reduces the amount of CoA he uses in Enma and finds the perfect balance to cut him with Tatsumaki. Problem is, now that he has the slash under control it ends up just being a shallow attack just like every other attack.
The reason why Ashura is the 'strongest' attack Zoro has and coincidentally the only one we see give Kaido a deep wound is because it's the only one that utilises CoC.
Given that we will most likely see Hiryu Kaen again when Zoro slays Kaido over the Flower Capital, expect Zoro to give Enma his new 'Ryuo'. (This time being CoC instead of CoA.)
If Ryuo is simply the idea of flowing haki, then CoA and CoC should both be things that can be flowed through Enma.
He will then be able to make Kaido 'fall' and his goal of 'slicing [Kaido] into pieces' would also be achieved.