A very impressive challenge!
You might like for Greece: Nikos Kazantzakis - "The Last Temptation of Christ" or "Greek Passion" which both exist as ebook as well as "Zorba the Greek" and if you ever saw the film, the book is much better
If you accept Nicholas Gage (who was born in Greece as Nikolaos Gatzoyiannis) as a Greek author you might have a look at his autobiographical book "Eleni"
For Germany: Patrick Süskind, Günter Grass and for Germany/Switzerland Hermann Hesse (he was born in Germany, lived and died in Switzerland)