The problem with a topic like this is that we're never going to reach agreement
Now I would say Havoc 5 should be dropped into Wild, and Wild 13 (for all that it's one of my favourite levels) should definitely not come later than its current position.
Anyway, I've drafted a reordering that I'm quite satisfied with. I've deleted the ten least interesting Tame levels (least interesting from the point of view of solving the level -- I apologise on behalf of the challenge solutions to these levels) to make room for other levels to be placed in Tame, leaving gaps in Wicked and Havoc that could be filled by new levels.
TAME
Tame 1, 2, 4, 5, 10, 7, 8, 13, 14, 18; Crazy 11, 12; Wild 17; Wicked 14; Havoc 10; Wild 8, 10, 16; Wicked 5; Havoc 6
CRAZY
Crazy 1, 5, 13; Wicked 9; Havoc 3; Crazy 3, 4, 6, 9, 19, 2, 7, 14, 18; Wild 9; Crazy 8, 15, 17; Wild 6; Wicked 2
WILD
Crazy 20; Wild 5, 13, 18; Wicked 8; Crazy 10, 16; Wild 2, 4, 19, 1, 7, 12, 20; Havoc 5; Wild 3, 11, 15; Havoc 9, 11
WICKED
Wicked 7, 20; Havoc 13; Wicked 4, 11, 12; Havoc 14; Wicked 1, 6, 17; Havoc 15; Wicked 3, 10, 13, 16; Havoc 8
HAVOC
Havoc 1, 12; Wicked 19; Havoc 18; Wicked 15, 18; Havoc 2, 4, 7, 16, 17, 19, 20