There are still a few things in English in the Dutch interface and there was a little mistake. I'm a noob so I have no idea if this already came to your attention.
Here goes
1) Under Over (About) the drop down menu mentions forums. The correct words is fora. One forum, two fora.
2) The pop up after you update the scripts is still in English "All scripts are updated." In Dutch that would be "Alle scripts zijn geüpdatet"
3) Under hulpmiddelen (Tools) the last option in the drop down menu is also in English. "Clear search history" should be "zoekhistorie wissen"
4) Under Opties (options) Voorkeuren has to be "Voorkeursinstellingen"
5) Under Hulpmiddelen (tools) there is something quite confusing (hence the reason I visited the forum).
It says gelijke kopieen (similar match) en exacte kopieen (exact match). Since gelijk en exact are pretty much the same thing, a better translation would be
"Verwijder soortgelijke resultaten" (similar) and "verwijder exact dezelfde resultaten" (exact)
Although I must admit it's kinda difficult to translate "match" into Dutch in this context. Currently it says "kopieen", but that means copy.
Maybe it's an idea to replace "match" with "results" like in the first option of that specific drop down menu.
1 and 4 are like really minor mistakes, but the correct spelling is really fora.
. Even though a lot of people use it like that.
If I bump into anything else, I'll post it here. I hope I was not being too arrogant.