Glad that format is working for you! It may stop working at any time, so if you want our advice, you’ve got it, and I think the peace of mind around changing one rule for 7 is totally worthwhile.
And you’re right - we would never ever add that particular header - our default caching is very carefully considered and your configuration (setting a long cache timeout) is a worst practice for most folks who do it without thinking it through. I guess you’ve probably seen this article, but in case you haven’t:
Not saying you need to change things - you seem pretty thoughtful and I guess you know you’ll not want to change a css file in the next year (though that seems quite suspect to me now that I say it out loud - for a font it makes sense, but really, for css?). I have just have spent so many hours troubleshooting for folks who set a timeout like that, and had to rename all their files to “dodge” their old, bad config - it’s super hard for us to debug since all we know is “that file is changed in our database” - we can’t see past caching headers settings easily.
But anyway, now you know the full story and can make the decisions that match your desired risk level and meet your goals best!