Cafe Belo. Still solid.
Okay, I ate dinner tonight at Cafe Belo, 120 Washington Street in Somerville, between Union Square and Sullivan Station. It's still a good place to get a good cheap meal! It's a Brazilian buffet, although becoming less Brazilian with every renovation. Good salads, plain cooked beets, plantains, arugula salad, cucumber salad, rice with octopus or squid, spaghetti bolognese, chick stroganoff, and I can't remember what else. And then, of course, really tasty grilled meats -- for me, roast pork and a delicious pork sausage, and for my companion, roast beef. It was not a "fine" meal, but it was a really good meal. My only complaint is that they didn't have any passionfruit mousse on hand, so I got the flan, which was a delicious ending to the meal.
If you're looking for fancy, look elsewhere. If you're looking for plain but really well-prepared, stop in.
Pampas changed ownership and I felt went downhill (nearby I was preferring Oasis even though they grill over gas), one thing they did add recently was pamonha (Brazilian version of tamales) which I wanted to check out but didn't get around. The original staff of Churrasco Grill and part ownership of Pampas moved to Pampas in Malden which did well with the churrasco but not so well on the buffet. That said I haven't been there in 6+ months so your mileage may vary.
For the original poster, everything you mentioned including the stroganoff and spaghetti are part of the Brazilian culinary home-cooking "canon." Arugula would be more common in Sao Paulo than say Minas, but exists as "rucola" (and frankly if the buffet is a bit more Italian that is probably because the current Brazilian novela Passione works in some Brazilian/Italian culture). Its really not less Brazilian, its what Brazilians eat as opposed to what you would see on a higher-end Brazilian restaurant menu.