Yes, some loanwords of French origin spelt with -ert are pronounced as if they were spelt -är. The three most common are konsert, dessert and kuvert (’envelope’).
Interestingly, I've heard all of those pronounced with the full voiceless retroflex stop, but mostly from senior citizens. I wonder if perhaps the standard pronunciation has changed during the past half century or so.
What do you mean by this, Devalantariel? Have you heard them pronounced with the "t" not being silent?
Yes, only very rarely but I have heard it. Do not use this pronunciation, though.
But the French for "envelope" is enveloppe. A couvert is a covering, or a piece of cutlery. Crazy Swedes!