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I just ran the hack on the fresh site and it works. This time I used the download package instead of manualy, easier. If you aren't using the default template you'll need to regenerate the forum templates and reset the blocks placement. Ignore the one template error that can't generate, it is rolled into the Recent Topics block.
A hint that I found, don't set a cache for the Recent Topics block if you want to include Private Forums (is configurable). Private topics will show after a valid user refreshes the cache. I found this same behaviour in other blocks that should behave differently via group permissions.
These hacks and more are likely high on the next release wish list.