Here "outer darkness" is a metonym for the place where God sends those who reject them. This is a place that is completely separated from God forever. See how you translated this in [Matthew 8:12](../08/12.md). AT: "the dark place away from God" (See: [[rc://en/ta/man/translate/figs-metonymy]])
"Grinding of teeth" is symbolic action, representing extreme sadness and suffering. See how you translated this in [Matthew 8:12](../08/12.md). AT: "weeping and expressing their extreme suffering" (See: [[rc://en/ta/man/translate/translate-symaction]])