Yes, you are right, I'm sorry for the somewhat misleading translation. But I felt "should" instead of "must" would be more confusing, because that would sound s

Yes, you are right, I'm sorry for the somewhat misleading translation. But I felt "should" instead of "must" would be more confusing, because that would sound somewhat like "the author would like that". Which he definitely doesn't. Anything longer wouldn't have fit the limit.