"How do you say" or when is level 6 no longer level 6
Just to get it straight.
Level 6 does not mean native speaker.
It does however mean that once tested and passed at level 6 that the language standard will be the same 150 years or even only 20 years from now, even if the person with a level 6 never uses the language again.
That means not having to say,
"how do you say?"
or
"whats the word for?"
or
talking about "otels" or "willages" or "elicopters"
or any word searching of any kind.
The fact is, that if a particular language is not your native tongue and you do not use it, you will not remain at that level.
When I was a child of 8 years I could speak Italian like a native, it was where I lived and went to school. But now 40 years later my Italian is limited to ordering a beer. So thats OK 
level 6 in Italian, yes?
There will be a fall off in ability. A level 5 will eventually become a level 4 and a level 4 may slip without noticing it to level 3. So I dont think a fresh level 6 will always be a level 6.
So maybe we should be reexamining non native speaking level 6 holders too.
I saw a really bad english BBC TV soap the other day, based in London. Their level of english as native speakers was only just a level 4 !!! It was a disgrace to the english language. Reminded me of the challange Harry Higgins had in the film "My fair Lady".
Maybe we should test native Londoners english too.
Whats wrong with taking a test every so often? We do it with our medicals because we know our health will go down.
Healthy today, dead tomorrow 