Welcome @Gerard!
I am German and thanks to Google Translate I can understand your introduction, because my Dutch is non-existent
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Of course, it is easier to communicate and use software in ones mother tongue. But in open source projects this requires contributions from native speakers. For the software there is probably a lack of Dutch contributions, thus the fall back for not translated content is English.
For the forum you have to wait if you get response from other Dutch users. Sometimes it just needs spark to ignite the fire.
I can create a Dutch sub forum here, if there is enough response.
The pro is clear, it is much easier to describe issues and discus in your mother tongue.
But the con is, that the community is limited and other language speaker are excluded. This means that issues have to be solved for each language and other language speaker can't profit from foreign solutions.
Concerning documentation, I think most browsers support website translation meanwhile, that's the easiest way to use the manual or wiki in any language. And of course the forum too.
I removed the email address from your post, this just creates more spam. Everybody can contact you private through your profile, there is a send email link.
Armin
investing less than half an hour into Search function can save hours or days of waiting for a solution