we used to climb down the stairs every day
We can "climb the stairs" going up, which to me suggests rather steep stairs. But we don't "climb down the stairs"
I suppose you could use other synonyms as well: "climb down", "descend". Maybe a native speaker can confirm?
By the way, this course often translates "a coborî" as "descend", but this isn't a word used much in everyday English. We just "go down" stairs etc.
True. It could be "come down" the stairs as well.