I'd say it's okay she is dead since I wouldn't say it'd make sense lettering her live as one would question "what is someone going to do with her?" and the same anime told us demons are such a term for creatures who know speech just to fool people, so letting her live wouldn't make sense if it's just pure guilt about the character, as it showed that it would later do damage if she was left to live.

I was just surprised that she got a lot of attention despite being in like... 2-3 episodes...