retegrity
I did some more testing. Triggerbot specifically doesn't activate when you don't have reach on the target. So even if you set it to 6 blocks it will be 3 unless you have reach hack active.
Other combat hacks (I tested Killaura, Multiaura and KillauraLegit) DO activate and 4.25 is noticeably higher than normal reach, but 3 still doesn't reach.
I found out that the wurst distance setting is measured in blocks away from the center of the entity without taking hitboxes into account. So for example a player's hitbox is 0.6 blocks wide, divided by 2 is 0.3 blocks extra blocks of distance. I tested triggerbot with 3.3 and that worked perfectly as long as I was not attacking diagonally.
Hitboxes are rectangular, not circular. This means that if you're attacking perfectly diagonally the extra gap is actually 0.424 given by the Pythagorean formula. And anything in between if you're not attacking perfectly diagonally but also not perfectly straight.
In conclusion there is no "vanilla" range in wurst. 3.3 will not reach diagonally and 3.424 will outreach straight.