Cashews are not legumes, they are indeed nuts. And while they are rich in omega-6 fats, humans never were meant to eat more than a few nuts a time. Carbs, well, that depends if you're restricting carbs or not, and again, don't eat so many nuts that the carbs will matter.

Almost all nuts have very high levels of omega 6 PUFA's in addition to other antinutrients. They can still be part of a healthy balanced diet but a general rule, nuts should be consumed in moderation.

The one exception is macadamia nuts. They are almost pure "good fat" and have very little in the way of antinutrients. They're almost pure fat though so as @Matt 11 points out, even with macadamias your diet should not be nut-centric.