In 1960 Fanis's grandfather was already in his 60s at least. But he meets him again in 2003...That would make him about 100 years old , but he did not really looked like it.
The "8 years old" Fanis is played by the same kid-actor, from 1959 in Constantinople to 1964 in Athens. Then his father refers that he is 7 years old at the time. So, it had to be 2 years old previously! Additionaly, dad also informs that the girl hadn't send a letter to his son for 2 years; that would mean that they mailed each other until the age of 5.
At Aishe's ballet class, the pianist that we see isn't playing anything close to what we hear.