For the time being there is only solution with tag. It is not exactly what you need, but in some cases it can be helpful.

The tag tries to fit all given content into a specified box and automatically goes multicolumn when it is not possible with a single column.

See pdf-generation-troubleshooting-f4/is-it-possible-to-toggle-multicolumn-from-page-to-page-t255.html

Alternatively you may split your document to single- and multi-column parts, convert them separately and merge the resulting PDFs into a single doc (usin PD4ML’s PDF merge API).