Micronesia is not a country. It's a region made up of multiple sovereign states, one of which is the Federated States of Micronesia. Either way, it doesn't belong on your list.
What people guess, how often they guess, and familiarity doesn't make it right. Micronesia is not a country. It's the same as people who refer to the Netherlands as Holland. If everyone guesses that Holland is a country, does that make it correct?
We are guided by UNGEGN, the United Nations body that maintains a list of long-form and short-form names for each country. This name list is not foisted upon each country, rather it reflects the names by which a country wishes to be known. The long- and short-form versions of Netherlands are Kingdom of the Netherlands (the) and Netherlands (the) (no "Holland" anywhere in sight). Other official long- and short-form names are United States of America (the) and United States (the); French Republic (the) and France; and Federated States of Micronesia (the) and, wait for it... Micronesia (Federated States of), which starts with M, which is good enough for us.
Wonderful research...kudos to you, but it still doesn't make Micronesia a country. Let's not go back and forth on this..maybe expand your clue description to include something along the lines of "short-form names accepted".