[x] van / von / ten

Dutch, German etc. names sometimes have "van" or "von" or "ten" etc. in them, which are not capitalised in conventional usage.

(Loosely, "ten" means "the" and "von" and "van" mean "of", as in "Robin van Loxley" and "Winnie ten Pooh".)

Would it be a good idea to reflect this on the db? There are two instances of personnel with names like this in the Maarten Altena Ensemble, for example. I consider it would be better to have them in as:

Maartje ten Hoorn
Peter van Bergen

... and so on.

Am I reiterating something we've been through before?

This is not necessarily true. Both the capitalised and non-capitalized forms exist. So 'van Bergen' and 'Van Bergen' are two different last names.
So are these:
Van Den Bergen
Van den Bergen
van Den Bergen
van den Bergen
Vanden Bergen

I'm not sure if the third and fourth one exist, but I have seen the first two and the last one.

MW,

We'll definitely change the capitalization of those names if that's the correct thing to do, but as Python pointed out, those things come in a variety of flavors.