User blog comment:ToastSoul/Cape Kaga/@comment-200.128.77.250-20160503122646/@comment-26009184-20160503131709

I never expected anyone to read that deeply into this, but that's a good point that never occurred to me. You're completely right about vermilion being used for wedding gifts because red-coloured fukusa are apparently used for celebrations. /wikiknowledge

Which brings up an entirely different issue, which is that you'd 'dying autumn' to be brown, not red (I had to google 'vermilion' when I translated this almost a year ago now, because who the heck uses the colour 'vermilion'). I'll change it back to 'vermilion' and then people can just google the colour.

Second part: I feel like はず is so strongly tied with expectations that a fair portion of the time it's somehow tied to doubts. If it really were "there's no way..." then I would expect something more along the lines of できるわけがない. In the end, they're really just two different interpretations of the same line though, so I suppose it would change based on the person reading it.