Wandering Traders have unused Age and ForcedAge tags. Most likely because their model, texture, and NBT data was copied from villagers. Side note: these tags are always valued at 0. If you change them, they instantly change back to 0. Why have these tags if: first off, there's no such thing as a baby wandering trader. Secondly, they are reset to 0 every tick, causing minor(depending on how many you spawned) performance issues.