First of all, thanks for posting what you did. It's made my life easier. I also have a need to have category titles (not descriptions) contain BBCode. I want to be able to set up menus, where each menu item will (invisibly) either go to a sub-category or to an actual album. But having all of the categories in one "block", and the albums in another - either above or below - destroys the "menu" concept. (Because, then, list items not only fall out of alphabetical order but have completely different visual presentations.) With your tweak, I can have a category title link directly to an album that's contained within the category - which gets around the "problem" of clicking on a category and then having to click on an album (with the same title) in order to get to the pictures that I'd like to get to from just the first click.
(It would be nice if Coppermine introduced "menu items" that could link to either a category or an album, or if an album could be set to display itself as if it were a category - but, without this, your solution is the best way of doing this.)
I still haven't figured out the breadcrumb display problem, but I do have a handle on getting the hyperlinks for category thugmbnails to link to the BBCode of the title, rather than to the category itself. The problem is that, for some reason I really don't understand, Coppermine actually contains two set of hrefs, one for the thumbnail followed by one for the category title. Since I've seen no indication that the thumbnail should ever take you somewhere different than the title, I really don't know why it was designed that way. What needs to happen here is to have a single href that contains the thumbnail followed by the title. The code for that is all already in place, it just needs to be tweaked a bit.
I'll be working on this tonight and hopefully post the "fix" then. (Although, as I mentioned, I don't even have a clue yet about the breadcrumb problem.)