“And, besides, since when does God do things on our agenda if everything is subject to fulfillment of His “plan?”
It’s not “our agenda” but according to His plan to perfect us. His plan was for Jesus to learn obedience by the things He suffered. Innocence becomes virtue by testing.
One doe snot become innocent. Either you are innocent all along or you are not.
When you say "His plan for Jesus" are you separating the Person of Jesus from the Person of the Word? Remember, one Person, two natures is the orthodox Jesus.
By asserting that Jesus had to "learn" obedience means that He had a potential to be disobedient. Did that potential ever exist? Was there ever a time when Jesus may have sinned through disobedience? Or was His human will always in perfect harmony with His divine will, even when He was still "unlearned?"
Innocence becomes virtue by testing
So, was Jesus not virtuous all His life? Was there ever any doubt in the same Person we call Jesus the Savior that His human nature needed testing in order to "become" innocent?