I think the HX are op because classes that can counter HX have been nerfed.
Archery: nerfed
HA: nerfed
Lance cav: nerfed
Now, they do not really have menaces against them.
In addition, apart from the "Horse Archery", they have no class weapon difficulty on their build.
I think to balance the things, crossbows should have some sort of PowerDraw.
And instead of constantly nerf, should be slightly buff classes that can counter them.