PARIS — “Playing it safe can cause a lot of damage in the long run.” The notion — one of Jenny Holzer’s “Truisms” — was in my thoughts throughout the Paris Fashion Week that closed on a cheerful note on Tuesday at Disneyland Paris, of all places, with another inconsistent Coperni show wrapped in charming, media-friendly theatrics. This was a “playing it safe” season, and it is not difficult to understand why: demand for luxury goods has plunged. Part of the problem is…