I think you are correct - those default fonts probably don't include the accents (you can see that accented Greek characters are grayed out). I don't know anything about the special Greek punctuation, so I cannot even tell (my knowledge of Greek expends to mere familiarity with Greek alphabet from the math classes in a Soviet school
). If the accents and/or special punctuation are a must for a modern Greek reader, one should read PDF, or LRF with embedded fonts (or "picture" LRFs converted from other formats by PDFLRF - then you will not have any paging delays, and you can read in any written language known or unknown to man, but the resulting LRF files will be larger by far).