Clover works with Java and Groovy languages. If you have code written in other programming languages, you could potentially generate XML/HTML/PDF/JSON reports for them as well. However, there are some prerequisites:
If all prerequisites are fulfilled, you could write a data converter from that coverage tool to Clover's database format.
As soon as you have the data converter ready, you could run it within your build to generate Clover database. You could also merge the resulting database with a database generated by Clover for Java/Groovy sources - thanks to this you could have a single, consolidated report. Next you can run Clover reporting tools to get reports you need.
And how the HTML report would look like for an unknown language? Well, you would see classes and methods as usual, but it Clover would use a plain text formatter for a source page (Clover has syntax highlighters for Java and Groovy only).