The logo is just Kas before being corrupted, don't think it makes any allusion to purifying her. Iirc in COC1 the only ending where you could purify the last boss was added in the revamp mod
They keep making references to how she didnt ask to be like this and appears to be bitter over it at times, desires more than anything to be a mother, and based on a few scenes desires a romance/deeper connection with the pc. That appears to heavily foreshadow a alternate route. On the topic of her art, yes it likely indicates her precorruption but I doubt they would put the effort of making it the logo if her being non corrupted didnt factor into the story in a big way.
My called shot is there are 4 or 5 possible end games for her.
1: You kill her
2: She wins corrupt ending
3: You win but enslave her as a corrupt ending effectively taking her place
4: You win and capture her like the rest of the corrupted characters you can do this with
5: You win and purify her some way.