Same thing in Turkey where we use the Turkish names which was used during the Ottoman Empire for most Greek Islands and some cities like Thessaloniki and Alexandropoulis.
Greeks do the same using the Greek version which was used during the Byzantine era for most cities including Istanbul and Izmir as you have mentioned.

However, if we come to this issue, yes, it's SAW and only applies to the lounge FIDS managed by BA. The airport FIDS would show Istanbul ( SAW ) correctly though.