No, and this is worth sitting with. Restaurant nutrition estimates can be off by 30–50% and still be genuinely useful. If a dish is estimated at 600 calories but the real number is closer to 750, you're still building an accurate-enough picture of how you eat.
The direction of the habit matters more than the exact number. Gatherer's data is an honest estimate, not a lab measurement, and an honest estimate used consistently is enough.