Harry Cornick gave the visitors a deserved lead as he converted from Dan Potts' cut-back after smart work from the Town down the left, but were pulled back when Joe Lolley fired in from just inside the box.
The former Huddersfield Town man put the Reds in the lead with an emphatic finish just after the break, before Grabban converted from the penalty spot late on.
Jones said: “It’s an improvement on last week, which is a bonus. We came here with the belief that we could get something. I don’t think everything went in our favour today.
“But overall I was really satisfied with the first half performance, certainly the mentality coming to Nottingham Forest, in their backyard. How we performed, how we controlled the game to an extent off the ball for the first time. It’s good to have Glen Rea back in there.
“Obviously we know what happened with the first goal, it could have been a free-kick. Second goal, Lolley has got that individual quality that a lot of Championship teams have got, it’s not about tactics or work, it’s about his ability to cut inside and find the top corner.
“James Collins had a good chance and Dan Potts had a great chance from a set-piece. It could have been a lot different.”