I recently had the same question, but I didn’t have a target so I just dumped the fruit in. I brewed a cherry brett saison. It is only the second time that I have used fruit. At least you read the can and found the sugar content. I never even read the can.
For your beer, I went into Promash and created a 5 gallon recipe with a gravity of 1.045. I then added 130 grams (.286 pounds) of can sugar to the recipe. The predicted gravity was 1.048. So, it doesn’t look like 10 points will be added by the fruit. In addition, there will be some water in the puree that will dilute the beer.
What caught my eye is that I only had 7.75 pounds of grains in the sample recipe, but the kit has 11 lbs. I am not sure what Northern Brewer allows for wort left in the kettle or efficiency. I adjusted the recipe (5.5 gallons with 70% efficiency) to 11 pounds of grain and hit a gravity of 1.054 with no fruit added. So, I am guessing there was something wrong with your calculations.
In the book American Sour Beer, Appendix B gives a formula, but the general statement is that adding fruit does not typically boost alcohol content significantly. If the beer is stronger, the fruit can dilute the beer and lower the final alcohol content.