Hah yeah that 'kay girl was damned annoying but I thought Sarah(?) the girl with the glasses was hands down the worst. Nothing like hearing "Faerie healing!" in her extremely annoying high pitched voice over and over and over... *feels the rage building*
I didn't have any problem with Reimi, Bachus, or Myuria's voice actors. But Sarah and Lymle drove me insane. For that matter, Edge (I think was his name?) wasn't that bad. I don't really see the whiny bit about him either, but perhaps its just been awhile since I played it, and forgetting something here? The cat girl was ok, but not really good.
I'd say if you liked tteot, you'd probably like lh. The grind isn't really any worse. Actually, it's better if you played some of that damn tower after you beat the game in tteot.
I would recommend at least trying the japanse voices though, especially once Lymlee gets introduced. They couldn't possibly be worse than the english version of those 2 mentioned above.
Oh, I did think the plot from tteot was better, even with the controversial "plot twist" introduced.