Loa: It's pronounced "low-ah" not "low". And the Loa aren't low-level fairies, they're the equivalent of gods. Papa Legba and Baron Samdi are (arguably) on the same plane as Hermes and Hel.
Exactly what accent was that "voodoo witch" supposed to have? I'm a mid-western American, but I'm pretty sure that whatever the hell she was speaking was probably insulting to anyone who has ever been within a thousand kilometers of Haiti (accepted center of Voodoo in the literary world).
But that's all forgivable pittance. The real insult?
Kenzi was abused by her step-father.
You just took one of the strongest, most interesting characters on the show (even outside the show) and turned her into a cliche victim. That is absolutely inexcusable. It is an insult to women, it is an insult to geeks, and it is an insult to anyone with an IQ over 50.
It was bad enough that this season started off with Kenzi going from "strong everyman" to "drug addict who just wants to be like the 'cool kids'." But... "Mom's boyfriend molested me"? That came out of nowhere, is contrary to established personalities, and—worst of all—implies that the only reason she's strong is because she was victimized as a child.
I am in no way a feminist, but even I find this to be insulting.
I don't know what happened behind the scenes between seasons 3 and 4, but it was a mistake. And it's cost the show at least one viewer.
 There are a few on these forums who will be happy to tell you—in detail—how they think I'm a mysogynistic sexist—without any concerns about the redundancy in that term.