It doesn't say "highly favoured one" - it says, "Kecharitomene".
When Jerome translated the Bible into Latin, he translated this title as “Gratia plena” (full of grace).
He could HARDLY write: “Hail, completely, perfectly, enduringly endowed with grace, which is a perfect passive participle, indicating a completed action with a PERMANENT result” - which is the definition of "Kecharitomene".
The SAME is true for when the KJV was translated - only, "thou that art highly favoured" was used in place of the actual definition.
“Full of grace” was simply the most concise way of explaining the above definition. Jerome probably didn’t think that it would be an issue. - nor did the translators of the KJV who held Mary is MUCH higher regard than YOU or your fellow 21st century anti-Marianists.
At any rate - I suggest yo do your homework . . .