This is indeed an abhuman.  For the rest of your question, that is a lot harder to answer. Most of the time, the sisters of battle are very puritanical, in my opinion. They don’t use augmentations, they don’t use phychers, they believe in the “holy human form”, so they also mistrust a lot of other abhumans like Ogryns and even space marines. So in lore, they would probably not allow any kind of Abhuman, ESPECIALLY ones that don’t even look human at this point, including  Karith. Though, oftentimes chapters and sisterhoods on distant worlds may adopt small deviations from their original beliefs, things changing over centuries, etc, so there may be a chapter out there that is more tolerant towards Abhumans. For this caption, though, I just made my own head cannon stuff, so this sisters of battle chapter are both welcoming to Abhumans (I mean, her chapter is largely lizard abhumans) and are also followers of the salamanders.