Balance: Nature's Grace bug

Im not sure if this is a bug or that's just how it worked back in the days, but i play a balance druid on warmane's outland tbc server, and my nature's grace buff pops up after i finish casting wrath, immediately, rather than when the spell hits the target and the crit actually happens. This is kind of frustrating. I dont know if was a way to know for sure that you are gonna crit before the spell finishes casting back then but same thing happens with regrowth on any raid frame addon that tracks incoming heals.. they just know its gonna be a crit every time, bevore i finish the cast. Any opinions on this?
Reason why it negatively affects my dps is because when i spam wrath for some quick damage i want to use the procs for starfire, but because of the bug i need to jump and cancel the chained wrath from the spell queue rather than doing a wrath, doing a second cast, first one hits the boss and crits, then i see the buff while still casting so i can chain a starfire immediatly after second wrath is done.. am i the only class having this early crit display, is tit a server wide bug, or just a druid specific? I would make a ticket but not sure what to say in it.. game is not supposed to predict that ur spell is gonna crit before it hits..

It wasn't like this on my previous server so i can't relate if blizzlike or not, but never jump to cancel a cast you started always finish it (except if he gonna break a CC)

Ps: the rotation you use (the best i used when i was moonkin in SW) need a lot of mana, i am not sure you can do it without ending oom (you need and exceptionnal SP or no haste)

There is another bug you can check too, early server melee crit was doing nature's grace proc too...