Instead of timing your attack ahead of time with the vanilla mace (extremely difficult learning curve, afaik)

I suggest having a custom attack with the mace, where holding down your attack keybind begins charging the mace, (only available while falling)

and either A) the mace will automatically land its attack when your hitbox overlaps with another's,
or B) have the player time letting go of the input to launch an attack at what's in-range, if any

I would suggest removing the upswing entirely for the mace. The current default behavior is very broken and makes the mace nearly useless. Just because people can change it themselves by making some datapack doesn't mean they want to, and it doesn't mean the default shouldn't get changed.

This can be achieved by creating a specific weapon attributes file with zero (or minimal) upswing ratio on the attack.
Such customisation can be added by anyone, using a small datapack.