The phrase "are rather slight" is correct and usable in written English.
It can be used to describe something that is minimal or not significant in degree or extent.
Example: "The differences in their opinions are rather slight, suggesting that they may find common ground."
Alternatives: "are quite minor" or "are fairly negligible."
The one chapter given to architecture is rather slight and not really focused on his churches.
Singapore's case law on the subject is rather slight, she says, and during the hearings judges seemed loth to break new ground.
The plot is rather slight (and reminiscent, inevitably, of so many other zombie tales), and the ending feels a little rushed; but the characters – especially Melanie and Miss Justineau – are so well drawn and so human that it's impossible not to feel for them.
In the context of the severe psychological transformations caused by a disease like Alzheimer's, this means that the appropriate level of prudential concern of the earlier and current self for one another would be rather slight.
Some may claim that Frank Loesser's score for Where's Charley? is rather slight, but I don't think that's very fair.
Rutgers-Newark English professor and poet Rachel Hadas described the poem as being "rather slight" although it "is free of irony and self consciousness, except that little reference to fools like me at the end, which I find kind of charming".
This study also showed that the strength of right-handedness for manipulative activities was much greater in adults than that reported in young children, whereas the difference with age was rather slight for pointing gestures.
But surely those of us in the reality-based community can at least agree this much: the media's causative link with massacres is rather slighter than that of lunatics having such easy access to the weaponry of their choice.
Both groups showed a slight improvement in this measure as training progressed, but there was rather little difference between them.
