Hello!
Breadcrumbs are primarily navigation for visitors. They should show one clear path through the site, not every tag, category, or taxonomy relationship a post has. Tags, especially, are topic labels, not a hierarchy, so they usually make poor breadcrumb items.
TSF generates one breadcrumb trail. For posts with multiple hierarchical terms, you can set the primary term to reflect how visitors should understand and navigate the site. For custom post types, I recommend using the taxonomy hierarchy that reflects the actual site structure.
If this is only meant to influence search engines, I would avoid it. Search engines are best served by breadcrumbs that match useful, visible navigation. Adding extra breadcrumb paths just because the post has multiple tags or taxonomies can make the page less clear.
What problem are you trying to solve for visitors? If they need to discover related topics, visible tag/taxonomy links near the post content are usually more helpful than multiple breadcrumb trails. If you have a specific visitor-facing navigation layout in mind, please describe it, and I can point you toward the best option.
I think of breadcrumbs as doors. Users and search engines can choose which door they want to use.
Our job is simply to create the door and tell them there are multiple doors.
I may be misunderstanding, but Google allows it.
