We appear to have "Nested" links in breadcrumbs_main.tpl {BREADCRUMBS_LINKS_RIGHT} rather than a chain of individual links.
So how do we split them into single url's ? Because if one adds a Nav Menu to the theme - one doesn't usually need or want the "text" strings where they are ? Except maybe "Mark all Forums Read", and / or "Mark all Topics Read".
I could probably dig it out, but the point is - for creating extreme themes, it's just another obstacle that has to be overcome when it could be made a lot easier.
And an example of what I'm talking about is here >> h**p://***.lopalong.com/forum/forum.php - Where I have been stuffing around with "Pearl Black Special"