Aramaic doesn't have a single, common word for "youthful" or "downy-bearded" that would translate directly to "Julie." If you were to find an Aramaic name with a similar meaning, it would likely be based on a different root and wouldn't be a direct translation of "Julie."
For example, you might find names like:
* Yohanan (יוֹחָנָן) which means "God is gracious" or "Yahweh is gracious" and could be interpreted as similar to "youthful" or "blessed"
* Eliyahu (אליהו) which means "my God is Yahweh" and could be associated with a sense of strength and youthful vigor
Ultimately, it's important to remember that names carry cultural and historical significance, and directly translating a name from one language to another might not capture the full nuance of its meaning.