if the static content is directed to the region-body of the page.
Is this even allowed by the spec?
2.) Similarly, the StaticContentLayoutManager should be renamed to SideRegionLayoutManager, because the output of both fo:static-content and fo:flow can be directed to it,
No, the latter can't happen. The 0.20.5 branch even tests for this and aborts in that case.
J.Pietschmann