Arguably, you might want to exclude the BTS and website from the tipping system (or give them a separate pool to draw from), if you're trying to encourage code contributions. Not that website changes aren't valuable, but it's far too easy to make a dozen commits to the website as a natural part of cleaning it up and working on it, especially given the way wikis allow live edits of only a single page at a time.

Could tip4commit support configuring a single repository to treat commits differently based on what paths they change?

As an aside, if you added a full name to ikiwiki's Preferences, couldn't you construct proper commit authors using full name and email for anyone who supplied them?