We have three themes which currently duplicate and override the bbwebsite_portlets.pt template of macros (mainly used for portlets) which is part of the bbwebsite product. These are:
These have their own versions of bbwebsite_portlets.pt. So when we create a new portlet in bbwebsite, add it by default to the site setup and then define new macros in the bbwebsite_portlets.pt template, we have to add them to the theme version of the file, otherwise these macros are missing which means the portlets calling them generate a TraversalError, which is basically a path call 404 or a template 404.
If you get a traversal error therefore, it's telling you that some call to some object via a path call such as here/bbwebsite_portlets/macros/someMacro is failing because the macro in question is not defined or can't be found.
The reason nothing shows up on the main site is generally because the portlets in question are set up to appear in a hidden column, and portlet errors don't breaks the site, they just generate a small error message in the column in which they should be displayed. If that's hidden, you'll never see it.