Give yourself a mace with wind burst level 4 through commands:
/give @p mace[minecraft:enchantments:{levels:

}}
Spawn a warden with a spawn egg
Hit the warden
Expected Result:
A wind charge should be summoned when the warden is hit
Observed Result:
There is no wind charge summoned

This can also be observed with Density levels above 5, and Breach levels above 4.
Density level 6 does the same damage as a normal mace when you fall from a height of 45 blocks to kill the warden in a 2x2 hole.
For breach levels above level 4, they act just like Breach Level 4.