Sorry to hear about this as the Hoge Veluwe reserve is very well managed and the boar, mouflon and deer numbers tend to be well controlled to ensure over population in the reserve doesn't occur. It's very popular with visitors, but the wildlife tends to stay well away and unlikely to get stressed. Not seen any wolves there, but a few foxes, it tends to have well maintained fencing around the area, but nature has a way of getting past obstacles like this! I would have thought the Boar would be used to noise as there's an Army training area in part of the park and the sound of automatic weaponry is err.... frequent and heavy. Where the BBC gets its numbers from I don't know, but 6,000 is way over the top! By the way, there is a great art gallery there and is a lovely place to walk or cycle if you're in that part of the Netherlands.
I have walked through the park and its really quite dry and sandy so whether it can support a bigger population possibly not. There may also be something lost in translation - Wild Boars just referring to the Adult Males. Even if this is the case then there will be similar number of breeding sows and perhaps 200 or 300 piglets as well.