Any targets for including in selmer must currently be known when selmer compiles the template, which it does without the passed in data. This means that, given the template:
template.html_template:
{% include right-page %}
and the clojure code:
(selmer/render-file template.html_template
{right-page "some/other/template/file.html_template})
You can expect an exception. As for a work around, you might consider
(selmer/render-file template.html_template
{right-page (selmer/render-file
"some/other/template/file.html_template {})})
or something similar.
You will, of course have to update template.html to include the already rendered text, and to disable escaping, like so:
template.html_template:
{{right-page|safe}}