Hi @belen_rojas ...
There could a couple reasons why columns in a rubric may not line up exactly. For example, if you had rating scales of 5, 4, 2, and 0 for some rows and rating scales of 10, 8, 4, and 0 for other rows...you could have completely different descriptions for what the 5-0 scales mean compared to the 10-0 scales. Even though there are four ratings per range, that doesn't always mean the columns will line up exactly...especially if the descriptive text is different. Another example is when I build courses for our faculty. Sometimes I'll see rubrics that have a 5, 4, 2, 0 rating scale...but then at the end there will be a 2, 1, 0 scale, too. So, we have a series of four ratings following by a few rows of three-celled ratings Those columns won't ever line up.
I searched around the Community for an existing Feature Idea, and I came across this one: https://community.canvaslms.com/ideas/12350-adapt-canvas-rubrics-to-conventional-rubric-design" modi.... If you feel that this Feature Idea aligns with something that you'd like to see implemented inside of Canvas, I would encourage you to vote on it and also consider adding a comment at the bottom letting Canvas engineers know why something like this would be important to you.
I hope this information will be of help to you. Please let Community members know if you've got any questions about this...thanks!