Isn't there an equivocal sense to saying "I have a backlog of (something)"?
I have a backlog of work and would be unable to help you out on that.
I have a few outfits that I haven't shot yet — have to keep up or there will be an unwanted backlog of outfits since September.source
I have a backlog of fruits that have been sitting in the bottom of the fridge for a couple of weeks now — have to eat them now or else they are going to spoil!
My main reason for making yogurt this week, though, was that I had a growing backlog of milk in the fridge.source
My main reason for eating a stick of butter every day, though, was that I had a backlog of these sitting in the bottom of the freezer.
vs.
I have a backlog of work which will keep myself, my designer and my technician busy all through the fall.
I have an unexpected backlog of cash which should keep my family and myself safe from necessity in these times of hardship.
Some states have an unexpected backlog of money which will enable them to award new grantssource
Some colleges and universities have an unexpected backlog of money which will enable them to catch up on the longstanding housing shortage.
I have an unexpected backlog of cash this year. I'm going to buy a Porsche!
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Best Answer
The meaning of "have a backlog" in both cases is exactly the same: "have a backlog". The bad news vs. good news difference comes from the words thankfully and unfortunately.
This works for any and all expressions, not just this one.