Strictly speaking, {ghevI'} just refers to gagh sauce and not condiments in general, though the metaphor probably works fine even if a specific condiment is named, so it's not a big deal.
Your translation seems fine in terms of getting the meaning across: "When one fails, the event makes success delicious, it's like gagh sauce." What sort of stylistic qualities are you going for? Do you want something concise? Something that's similar to the structure of the original? Something that avoids {-ghach}?