Hi, you should file this coin under Eastern Caribbean. You're right as to the fact that it's not a country, but it's a group of islands, such as Antigua, Montserra and so on. Because they have and use the same currency, they are all filed under Eastern Caribbean, and none of them bears a specific country name, though they are in use in different islands. That coin is already in Numista.
Regards,
Ginger
Si tu cognes ta tête contre une cruche et que ça sonne creux, ce n'est pas forcément la cruche... lollll mon proverbe préféré !