Try downloading the Noto family of free fonts from Google. Noto is short for "No Tofu," and refers to the fact that they contain most/all Unicode glyphs, so you don't get tofu (a blank box or gibberish) when calling for a special character. Once downloaded, put them in a folder called "fonts" (no quotation marks, lowercase "f") beneath the root directory of your Kobo, and then select either Noto Serif or Noto Sans as the font to use with the ebook you are reading. If it works, then the problem is with Kobo's version of Garamond.
https://www.google.com/get/noto/
Also, Markus Dohle is the CEO of Penguin (my publisher); you might perhaps think twice about impersonating him.