ΚΕΚΡΩΨ, somehow you missed these objective criteria that are recommended to be used:  "Is it the official current name of the subject? (check if the name is used in a legal context, e.g. a constitution)" Yep, it's in the constitution. "Is it the name used by the subject to describe itself or themselves? (check if it is a self-identifying term)", Yep, it's self-identifying term. And let me quote something else from that policy: 
 Subjective criteria (such as "moral rights" to a name) should not be used to determine usage. These include:
 Does the subject have a moral right to use the name?
 Does the subject have a legal right to use the name?
 Does the name infringe on someone else's legal or moral rights?
 Is the use of the name politically unacceptable?
This pretty much invalidates most of arguments used by the Greek side. What remains that FYROM is more popular than Republic of Macedonia? That has not been concludently proved and might not be even important since. 1. it's not established that FYROM is used widely in English, 2. we have a self-identifying term that doesn't need disambiguation, so where is the problem to use "Republic of Macedonia"?