The increase of damage based on how far you fall with the mace and its density enchantment is not affected by the attack speed cooldown of the weapon.

How to reproduce:

1. Spawn a warden with no AI on the ground (it doesn't need to be a warden, but it's easier to notice the issue this way).

   /summon minecraft:warden ~ ~ ~ {NoAI:1b}

2. Pillar up at least 20 blocks (it's easier to notice the issue the higher you pillar up).
3. Give yourself a mace.
4. With your mace fully charged, fall from the pillar and hit the warden.
5. Use the following command to find how much health the warden was left with:

   /data get entity @n[type=minecraft:warden] Health

6. Kill the warden by some means and repeat steps 1-3.
7. Fall from the pillar again and before hitting the warden, swing at the air to start the mace's cooldown and hit the warden while your mace is not fully charged.
8. Use the command from step 5 to find out the warden's health and compare it with the previous warden's health.
   → The health difference should be at most 4-5, which indicates that only the mace's base damage was affected by the mace being on cooldown, not the smash attack's damage increase.

Expected result:

The smash attack's damage increase would be reduced since the mace is on cooldown.

Observed result:

The smash attack's damage increase is the same no matter if the mace is on cooldown or not.