Getting a COA registered

[MacMillan of Rathdown]

But that's not the case, Scott. Focusing just on Europe for the moment, there are government authorized heraldic authorities currently operating in Belgium, Ireland, Slovakia, and the United Kingdom. There is one in Russia, but it is their current policy not to involve themselves with personal heraldry. There are no sanctioned heraldic authority in the Czech Republic, Denmark, France, Germany, Macedonia, the Netherlands, Norway, Poland, Portugal, Serbia, Sweden and Switzerland. These are all states where there is, however, some level of heraldic activity. Are you really suggesting that the people who bear arms in these countries are not "valid" in doing so? Seriously?

Seriously? Your question leaves out a lot of very pertinent detail. There is no blanket "yes" or "no" answer, and any answer will depend on a variety of conditions:

(1) Heraldic practices are not uniform throughout Europe.
(2) Every time there is a regime change in a country, the heraldic practices are subject to alteration.
(3) In most European countries heraldry is the sole prerogative of the sovereign or head of state, be it a monarch or an elected official; in some countries, it is the sole prerogative of the government.
(4) Virtually every government in Europe has a "department of heraldry" hidden away in the bureaucracy of it's civil service. While most do not concern themselves with personal heraldry, they are actively creating civic and governmental arms on a regular, almost daily, basis.

So, and I am speaking only about the present time, in those European countries where a monarch is the head of state, there are valid heraldic authorities who function not as officers of the government, but rather as officers of state. The degree to which their function intrudes on the life of the nation is determined by a combination of national custom and law. It is wrong to compare the heraldic practices of the English monarchy to other countries, and then deduce that no heraldic authority exists, when in reality one does exist-- although it does not function along the expected lines of the English model.

In those countries that in former times were monarchies (and this includes the states which comprised the Holy Roman, Austrian, Russian and German Empires) but which, through the vicissitudes of regime changes, are no longer monarchies, the status of all armigers created under the ancient regimes remains valid, ie: substantive. If it were not so, those Irish armigers whose status is dependent upon grants made by the former Ulster King of Arms would now bear arms that would no longer be considered substantive.

In those modern states created since the end of the Second World War, where there is an active interest in armoury, but where no state heraldic authority exists to grant personal arms, then the question of assumed arms hinges on the heraldic practices of the ancient regime. If it was the custom to allow non-nobles to assume arms without undue interference, then there is no reason why that practice should not continue under the exact same rules as existed under the ancient regime. Whether or not these arms would be regarded as substantive would be based entirely on local customs and law as it existed under the ancient regime.

If, on the other hand, during the ancient regime, arms were strictly regulated and there was a prohibition on their assumption, then it would stand to reason that both culturally and historically there would be no basis for the assumption of arms and that any arms assumed, since the fall of the ancient regime, would be lacking in substance.