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Majority of sealed games in Europe where sticker sealed (black Nintendo seal) almost all of them are FRA, FAH, or HOL coded. (and of course PAL A)
I have a list of the sticker sealed games, that is probably not yet complete
I believe that sticker sealed games come directly from Nintendo, they where already in two languages (Dutch and French) and could be distributed over 3-4 country's without any need to replace manual with another language (But this is just a theory). I also think that a local distributor has a big role in this, that's why there different approaches of how to package in different country's. In Scandinavia and German speaking country's where no sealed Nes games, in France, Belgium, Holland and French speaking country's in Europe we had sticker sealed games (but only a selection of them). In Spain they had cello sealed games.
Other speculations about sealed games are law requirements. In France when you buy a product it has to be new and unopened. So that also a reason why they had blisters in France.

The cello sealed games, as far as I know, where no releases. They where sealed by distributors (they could order cello sealed games from Nintendo, but it costed more) or big warehouses. There are even some games that are double sealed, black sticker seal and cello. Most cello sealed games you see today are ESP games, and almost all of them come form warehouse old stock.

So it's still a bit mystery, all we have are speculations.

As I wrote above, distributor could order sealed games from Nintendo, so probably Nintendo sealed the games. It is also possible that warehouses sealed the games after they got it from Nintendo. So no one reseals them if they come form in the box like this:
If you open the box, all the games are cello sealed. So most reasonable explanation to that it were sealed by Nintendo.