Are U.S. governmental reports a reliable source of information to cite?
There is no single such thing as "a US government report": the US government is a vast and complex organization with lots of different elements writing lots of different types of reports for lots of different reasons.  These reports range from absolutely standard peer-reviewed scientific papers to high-quality primary data to informational digests to purest propaganda.  As such, you really need to specifically attempt to understand the context of a particular report in order to know how to interpret it.

In the particular instance that you cite, for example, it appears that this is part of a yearly assessment prepared for Congress by the US State department as a digest of primary source material gathered by various US embassies.  Thus, I would recommend considering it as primary source material which attempts accuracy but not the results of a scientific study.  You will have to assess for yourself what credence to lend to particular elements thereof with respect to the use you wish to put it to.