They were ~340 years old 60 or so years ago, so today Jarul would be more than 400 years old if he's still alive. But yeah, I also think that the Gorosei aren't from the Void Century, since they already showed that they're unaware of a few things, like the reason for changing Nika's fruit name.
However, the Void Century happened 800 years ago, so it would be a huge gap (400 years) with no "Warrior Gods"... I feel that Imu just picked the best among his God's Knights from many different generations in those 800 years. Jarul and Jorul could've been considered the oldest warriors because people don't really know much about the Gorosei (or even CDs in general), they might think that they're just regularly old or maybe they aren't even warriors, they're just seen as statesmen/politicians. So, Jarul and Jorul were the oldest warriors of the known world.