You are a true polymath, wideawake!
I would add that when Daniel lived in the Babylonian captivity Greek-speaking Ionians were a well-known presence in the Empire, and had been known in the region for centuries.
The Ionians were known as Yavan in the Torah and were known as Yawani in the Indian Mahabharata - and historical-critical "scholars" more or less unanimously agree that the Mahabharata was written (1) at the same time as the Biblical Daniel lived and (2) a thousand miles further away from Ionia than where Daniel lived.
I would think the existence of the book of Daniel in Dead Sea scrolls would put that to rest.
Physically, the Dead Sea copies of the BOD were written somewhere about 150 BC -— the hammer period of the Maccabees being just 15ish years before this.
The isolated hermit folks that wrote and preserved the DSS just don’t strike me as the kind of folks that would incorporate some brand new book of the Bible.
Ergo, I’m with you. 550BCish