Hm, according to
gtp.gr (usually a pretty reputable source):
Twenty-eight lighthouses in Greece will be open to the public on Sunday, August 18, on the occasion of International Lighthouse Day, the Hellenic Navy has announced.
The lighthouses in the following 28 Greek destinations will be open to the public from 10am to 8pm:
6. Gerogombos – Kefalonia
That's on the Paliki peninsular.
I think they may have used old information, although equally it could be Gerogombos that's open and not Fiskardo