Nice to hear that you like it
. The reason why there is a light bleed is because Kobo forgot to apply the electrical tape at the sides. Here is a video (
https://www.youtube.com/watch?v=sxqVLnosNTI) on how to solve it, if you are willing to risk taking your Clara apart. I've never tried it before though, so just a suggestion.
As for the font boldness, are you referring to the in-built fonts? If you are, when you are in a book, press 'Aa' in the in-book menu, and on the right of the word 'Font Face' there will be a word 'Advanced'. Click on it, then there will be a slide bar for 'Weight'. This will increase the boldness. (Note: This only works for the fonts 'Amasis, Avenir Next, Caecilla, Georgia, Gill Sans, Kobo Nickel and Malabar. The other fonts require downloading something but I'm not sure about those.)