Do you mean it when you say restoration by a licensed professional? You must mean in Japan them right because there aren't any licensing requirements for knife makers in the US are there?
I mean everywhere, but only in regards to Nihonto or genuine Japanese swords. This has has nothing to do with Knife Makers anywhere, Japan, US or EU, etc..
Knife and tool makers even in Japan are not licensed by the ministry of culture.
Nihonto or the Japanese sword is considered a cultural art asset and carries a cultural status far above mere knives or knife making.
One of the fundamental differences between Japan and other countries is Japan requires proper education and licensing for many cultural activities such as becoming a sword smith or sword polisher.
You must first become an apprentice to a licensed smith or polisher.
You must complete that apprenticeship, enter government sanction competitions until you are determined competent to perform independently.
Then, and only then is one provided with the proper licensing and is able to work own his own within Japan.
Sword smith's must apprentice for a minimum of 5 years, sword polishers 10 years.
That is why there is only one licensed Japanese sword smith and two fully licensed Japanese sword polishers in North America.
Sadly, as you noted there are no governing requirements here.
You can apprentice a year or two, return to the US and call yourself a sword polisher, though calling a Volkswagen a Mercedes doesn't make it so!
Outside Japan, such as here in the US, many knife makers make replicas and variations of Japanese influenced swords.
Is there anything wrong with that, no. We have freedom of expression and can make what ever we like.
However, IMHO, the fine line is knowing where freedom of expression and spreading misinformation overlap.
Unfortunately, freedom of expression often leads to the spread of misinformation regarding things like terminology and nomenclature.
This spreading of misinformation may not be a malicious act, yet it yields in the same end result of incorrect knowledge being spread and accepted by those seeking knowledge.
Look through this site, you will see a wide variety of blades with Japanese names.
Does that make them Japanese, no. Is the terminology correct, many times no. Again, calling a Volkswagen a Mercedes doesn't make it so!
It is very important if you are interested in the hobby of Nihonto, to correctly learn the basics.
My advise would be to seek out a more specialized site if you wish to learn about Nihonto.
http://yakiba.com/beginner_page.htm