[kosta50]

Her being infused with grace did not change the fact that she still (1) could choose to sin (but did not)

Hermann, that is not what I read in Latin sources. What the RCC in essence says is that she was born free from any propensity or desire to sin.

[Hermann the Cherusker]

What the RCC in essence says is that she was born free from any propensity or desire to sin.

Adam was so created, and yet he fell, as did Eve.

St. Mary did not fall because she chose otherwise, having already experienced the excellence of the glory of God. She did not desire sin because she had already experienced a stronger communion with God than any allurement of sin might offset. She was perfectly free to chose otherwise, but she didn't.