When in doubt, just contact the hotel.
Nah dude I'll just ask strangers on the internet
Sometimes they charge on arrival, sometimes at booking and sometimes when they confirm your reservation.
Only way to know for sure if your reservation got through is contacting the accommodation
This happened to me as well — I called and they were able to confirm they saw the reservation. I hear you that it’s a little stressful!
Is inconsistency a common occurrence in Greece? Yes
This happened to me with all 3 hotels I booked lol. I just emailed them and they ended up charging it or telling me when it would be charged. Some of the island hotels are operating differently in the off season.
When in doubt, just contact the hotel.