It was accepted when I tried it. Do make use of the "Report a problem" button to point out such issues, and it will get fixed a lot quicker than if you just post a comment about it...
I'm trying to understand when it is expected to use "used to be" and when it is expected to use "were." I can't tell if there's a general difference, or if they deal with specific situations. In English they seem synonymous. But when I put "We used to be walking forward" I was marked wrong here. In English "We used to be walking forward" would be used in a situation with some testiness, like "We USED to be walking forward, but then you had to go following that woman." Is there a used to/were difference of similar emphasis in Spanish?
It seems that "were" leaves the possibility of continuing in the present while "used to" confines the action to the past. "you were good" has a different connotation than "you used to be good".