Fellow exjw here, I'm of Greek origin and studied 3 years ancient Greek language in college I also run the JW UPDATES youtube channel.Great research and explanation. This verse always fascinated me but there was something about the Watchtower's explanation that never added up for me.Let me explain.The verb dia-pthiro (=thoroughly + corrupt) is used for both symbolic and physical corruption in the New Testament. SYMBOLIC :διεφθαρμένοι τόν νοῦν, 1 Timothy 6:5, corrupt in the mind, or deprived LITERAL:Luke 12:33 GRK: οὐδὲ σὴς διαφθείρει, describing a physical treasure being destroyed What about Revelation 11:18, is it literal or symbolic? In thus case what is being corrupted defines its meaning. The EARTH is being
corrupted.In the book of Revelation 2 words are used for the word earth γῆ=gé (=the physical earth) AND oikoumeni(= the inhabited earth). In this verse the first is used γῆ=gé is used so the corruption is done on the actual Phyisical planet. Now it gets even more strange and interesting, WHO is corrupting the earth, several groups are mentioned are mentioned and excluded in the verse.The nations (=the un-redeemed people)The deadYour servants the prophets The people who revere your name, both great and smallSInce in the book of Revelation the people are divided to those who serve God and those who don't that pretty much covers all human kind Which leaves us with the "THOSE"Who are destroying the PLANET EARTH ,or as the ESV renders it:"for destroying the destroyers of the earth.”I believe them to be Satan and his fallen angels that are thrown down to earth in the last 3 1/2 years of the Great Tribulation and they only entities that can harm the planet thoroughly in ways that remains to be seen.