You need to include a column-count in your fo:region-body like this:
<fo:simple-page-master master-name ="page-first"
<fo:region-body margin-top ="5cm"
. . .
I haven't seen an example for this but is it possible to have one or
more blocks in which text flows into the next column, as in a
newspaper for example.
I am trying to do a two column A4 newsletter and don't want to worry
about inserting column breaks....