I've started new wikis and they have never shown up on my profile. It always says the same two wikis. Will the other ones ever show up? I've done a lot of edits on them too so there is no reason that they shouldn't show up I would assume.
As far as I know, the rules of which wikis appear on the "favorite wikis" list are not public. You can delete entries by editing your BIO form but not to add. I'm also not sure if UCP wikis appear there.
If you want to see a list of all the wikis you were participating on, go to your profile here on Community Central and click on the User Activity tab.