'is rarely reported' is correct and usable in written English.
You can use it to express that something happens infrequently. For example: "Success in this situation is rarely reported."
In Spain this condition is rarely reported.
Such asocial learning is rarely reported for flock animals.
Pregnancy, the most relevant outcome parameter, is rarely reported.
However, this application is rarely reported in the literature.
Whereas renal angiomyolipoma (AML) is common in TSC, renal cell carcinoma (RCC) is rarely reported.
To our best knowledge, such an interesting lubricating mechanism is rarely reported.
For kidnapping, which is rarely reported, the figure might be even higher.
Such field performance of modules, particularly spiral-wound sweep modules, is rarely reported.
The cell formation problem based on operation sequence (ordinal data) is rarely reported in the literature.
However, successful channeling of large volumes of regurgitated fluid by PLMA is rarely reported.
However, the role of interface contact is often neglected, and is rarely reported to date.
