True, the reload time is not documented as far as I know. It will be added to the FAQ.

With the mirror settings, the second FAQ point for a local site is closer to what you want. If the site you list first isn't found, it will fall back to the second site. Which means you could probably get what you want by listing your local archive as the second site on your list.

But I see you have sent mail to the list, which is probably best for discussing features in detail (I just include this reply for anyone else reading the thread).