"Now, she (Earlene Roberts) gives different time variants; two minutes, three minutes, four minutes, five minutes, whatever. She qualifies it all by basically saying he was back there long enough to grab a jacket."- Bill Brown
In her testimony she did not give different time variants. She said twice that Oswald was in his room for about 3 to 4 minutes and on both occassions she connected it with her previous testimony that he left the house zipping up a jacket, by saying that he was there long enough to grab a jacket.
So, there is no qualification. It's a remark that implies that Oswald did in fact go into his room to grab a jacket. She could have said "he was there long enough to change clothes", or something similar, but she didn't. By presenting her remarks in the way you did. you placed the emphasis on your (and her) conclusion that he did indeed go to the room to pick up a jacket, but except for Roberts saying it, there is no corrobarative evidence for that.
In other words, you presented Roberts' guess, about why Oswald was back there, as if it was a fact that he grabbed a jacket.