How to create a Personal Book in Greek Best Way?

Sascha,

I might be wrong, but my understanding is as follows:

• The Logos PB compiler will use the MS Word language setting for the resulting resource text language(s). Note the plural: those can be multiple languages in a document (as when an English language document uses Greek, Hebrew and Latin words, or citations from other language sources). So - regardless of the compile language - the resultig text will be in the language set in Word (if there is none, it may default to the compile-language - I'm not sure of that). 
  When is this relevant? E.g.
• when you double click on a word (or use the information tool) and expect Logos to open up a lexicon/dictionary in the right language. L6 should look up English words in the OED or MW, Greek ones in BDAG or in an analytical lexicon containing all Greek word forms.
• when you want to search only text in a certain language (there was a discussion prior year-end about Logos' additional language "Translit" - still didn't get to try editing the docx xml source to find whether I can force this into a document)
• The Logos PB compiler will use the compiler language setting to automatically identify bible references by the respective language's bible book names (and abbreviations) as well as scripture citation schemes.
  You know that, Sascha. German will pick up Johannes 3, 16 -  English will pick up John 3:16 and Greek would catch something with ΙΩΑΝΝΗΣ (never tried that).
  

Therefore I would format Greek texts in Word as Greek (and English-language intro text as English etc) and set the compiler language in a way that helps autodetecting bible references or in line with an editor's publishing language. If there are non, and no editor's remarks but just Greek text (say from Homer), I'd probably leave the compiler language at default English.