Pulse berries and sugar in a food processor until finely chopped. Transfer to a sieve set over a bowl. Drain for at least 30 minutes, or up to 2 hours. Reserve juices.
Preheat oven to 425°F. Roll out dough on a lightly floured surface into an 11-inch round. Press into a 9-inch tart pan with removable bottom. Trim edges of dough. (You can prepare dough to this point up to 2 hours ahead; refrigerate.) Line dough with parchment; fill with pie weights. Bake until crust is firm, about 10 minutes. Reduce oven temperature to 375°F; remove parchment and weights. Bake until crust is lightly browned around edges, about 7 minutes more. Cool for at least 10 minutes.
Spread cranberry mixture over tart crust (reserve juices). Arrange apples and pear in a circle over berries; dot with butter. Bake until fruit has softened and edges are golden brown, 45 to 50 minutes. Let cool.
Pour reserved juices into a small saucepan. Bring to a simmer over medium-low heat. Cook until syrupy and reduced to about 3 Tbsp., 5 to 10 minutes. Brush tart with glaze. Cool before serving.
