Got it on your premise and the arrow off page. I wondered about that as well.

When blocks was introduced I had a zoom call with Xara. They asked what are some of things you want blocks to do? I responded that I wanted to bring a block into a free form design. I think that was a naive answer.
Acorn answers it well. You need a good basic grounding of Xara best practices, because as Chris M has shown, when things go wrong, they really go wrong.