There are many errors in the Greek text. The most common problems seem to be mistaking ω for w, υ for ν, and using ϕ (U+03D5) instead of φ (U+03C6). A few examples from preface-2.xhtml:
Current
Expected
ω̂̔ν καὶ νν̂ν
ὧν καὶ νῦν
τŵν πολιτŵν
τῶν πολιτῶν
σωϕροσύνη
σωφροσύνη
And it almost always uses the circumflex accent instead of the perispomeni. Although the accent is commonly known as the circumflex accent, the perispomeni is usually rendered as a tilde or an inverted breve.