Add frozen should be fine. Unless you want some added flavour from the roasting. Frozen is quick and tastes good nevertheless. A handy thing to have in your freezer.
I'd never bought it before but roasted some the other week and it went rather mushy because it was in very small cubes. It tasted fine and saved a lot of time.
Just use it from frozen in soups or stews . Or just boil to make butternut mash . Lovely on a cottage pie. Or you can roast it from frozen just toss in bit of oil. It will mush be tastes lovely .
Some recipes for, say, butternut squash soup roast before making others just chop and add. I’d look at the dish you are making and roast it, if that’s what is wanted or not. It’s just chopped and frozen. If I have a large butternut squash and only want half I roast and freeze it as I can add it directly to risotto. When I’ve had a bag of frozen I’ve just used it as is.