Preheat oven to 425°F. In a small bowl, whisk together maple syrup, miso, oil, brown sugar, and red pepper flakes.
Line a large, rimmed baking sheet with foil. Arrange carrots on baking sheet and drizzle maple syrup mixture over top. Season with salt, toss to coat, and arrange in an even layer.
Bake, tossing halfway through, until carrots are tender and glaze is thickened and caramelized in places, 35 to 40 minutes.
Remove baking sheet from oven and carefully sprinkle carrots with lemon juice; toss to coat.
In another small bowl, combine pistachios, sesame seeds, coriander, and paprika.
Transfer roasted carrots to a platter, scraping any glaze from the sheet tray over top. Let cool slightly. Sprinkle with pistachio mixture, more red pepper flakes, if desired, and flaky salt. Serve warm or at room temperature.