That’s also how I understand it. The Konqi design by Tyson Tan is licenced under Creative Commons BY-SA, GFDL and LGPL. The page with the background story of Konqi, Katie, and Kandalf is also licenced under Creative Commons BY-SA.
CC BY-SA means that you would not only need to credit the author but also “ShareAlike” which means share derivate works under the same licence. I am not a lawyer, but the way I understand it that explicit usage of this licenced material in your novel requires that these usages of the material are also shared under CC BY-SA.
If my legal understanding is correct, this means that you not only need to write something like
in your credit section, but also make clear that the sections in which this material is used is also licenced under CC BY-SA. A practical example would go like this:
In your adventure novel there might be a section where the appearance of Konqi is described and you are basing this description on Tyson Tans work. It is also clear from the description of Konqi that he has character traits similar to what is described in Konqi - KDE Community Wiki. So in short, your character really is Konqi and not just a random dragon with the same name. Then, from my understanding, the sections of the novel in which this character acts also need to be licenced CC BY-SA. If these characters only appear on a few pages, this is easy. You simply write in your credit section something like:
The pages 23-24 in which these CC BY-SA licenced characters appear are also licenced under CC BY-SA.
This would mean that random people could freely put those pages on the internet for everyone to see.
If you planned to release your whole novel under CC BY-SA, there is obviously no problem either.
However, if Konqi, Katie, and Kandalf play major roles in your novel, e.g. because Konqi is the main character of the story, but you don’t want to release your whole novel under CC BY-SA, you should probably try to contact the original authors of the material you use for permission. Simply write Tyson Tan an eMail asking him if you have permission to use his design of Konqi as source material of your own original novel without the CC BY-SA licence restrictions on your textual use. If your Konqi has similar character traits as the one described in Konqi - KDE Community Wiki, you might also need to try to figure out who came up with those (I am sure some long-time KDE contributors would know) and if using such a character in your novel is allowed.
But that’s just how I understand it. Sorry that this might be a bit complicated. I am sure your usage of these characters is actually good for KDE, so if I had any say in this, I would give you any permission that I can, but strictly legally speaking CC BY-SA does not allow you to simply use the licenced material like it was your property to sell.