The phrase "rather rarely" is grammatically correct and can be used in written English.
You can use "rather rarely" to indicate that something occurs infrequently, but not extremely rarely. It conveys a sense of occasional occurrence. Example: "I rather rarely go to the movies, but I do enjoy them when I do."
Rumination is sometimes described as rare, but has also been described as not rare, but rather rarely recognized.
Rather rarely do novelists make their dreaming characters express, like Anna Karenina, their desires rather than their fears.
People in novels rather rarely eat; their health is not often of concern to them; earning money isn't nearly as important to them as it is to those of us in the real world.
Another category of pores with a diameter of 605 ± 101 nm was rather rarely found.
Unlike auroral arcs, which are indeed the predominant form of auroras, omega bands are observed rather rarely.
Compared to the investigations of the traffic effect on the static force coefficients, its effect on the aerodynamic derivatives is rather rarely studied.
For many, the level of discomfort may be somewhat amplified, but the pros of sticking in there continue to outweigh the cons, not just because of financial reasons, but because of loyalty to colleagues and (rather more rarely these days) a feeling that it may still be possible to turn their particular oil tanker around.
I actually pretty much loathed the programme, as it was rather formulaic and rarely biting.
Compared with this superbly sustained narrative drollery, Douglas's much-vaunted wit — vouched-for rather than experienced — rarely sparkles in the way that his reputation claims and the book demands.
Photograph: Tristram Kenton The chance to see Chekhov performed in London in Russian comes along quite rarely, rather like the occasional deliveries of toilet paper I remember seeing in Moscow shops under Brezhnev.
His inclusion is a clear sign that England have concocted a strategy based on bounce rather than swing; rarely can such a tall trio of fast bowlers as Steve Finn, Stuart Broad and Tremlett ever have been gathered together in one squad.
