It's difficult to judge about the story elements without knowing the background and what is to come. Maybe there is a reason for Kithraks behavior, maybe not.
I don't have a problem with meeting the Giths early. In a relatively open world, that's a danger you have to deal with. You know that they are dangerous and should be avoided as much as possible, at least that's what I did. I never trusted Lae'zel in her uncritical admiration to her kin, judging from her behavior and what she tells. Is there a use of being released from the tadpole while being killed?
I fought the Giths once, from the dialog (fight preparation with pre-knowledge in mind for me is absolutely out of order), when I used a mod to open up the level cap. As I saw that they were level 5 I did it with my party at level 5, but using only level 4 abilities (so, tier 2 spells). I won, with difficulties and perhaps luck. The higher hp alone helped, with the use of tier 3 spells it would have been an almost easy fight. So in release they should be manageable at level 5.
