You interpretation of verse 10 has no authority, as mine also does not have, but it does not have to read as killed.You left out verse 10.
Isa 53: 10 Yet it was the Lord’s will to crush him and cause him to suffer,
and though the Lord makes his life an offering for sin,
he will see his offspring and prolong his days,
and the will of the Lord will prosper in his hand.
Isa 53 is about someone who suffered and died bearing the sins of people etc
Verse 10 tells us that the Lord made his life an offering for sin. This means that he was killed. That is what happens with the offering for sin in the law. The offering is killed. So after his life is made an offering for sin, he will see his offspring. Baha'u'llah did not die and rise again to see his offspring and prolong his days. Jesus did that.
Both the Messages of both the Bab and Baha'u'llah were crushed from the land of their birth, the Bab gave his life as did Jesus, Baha'u'llah gave all his life as a Messenger in persecution, and imprisonment suffering many afflictions.
You can try many if the prayers that Baha'u'llah left us for forgiveness.
Prayers for Forgiveness - Baha'i Prayers .ca
These are the Baha'i prayers for forgiveness. I am aware, O Lord, that my trespasses have covered my face with shame in Thy presence,
bahaiprayers.ca
Abdul'baha took the Revelation of Baha’u’llah from 1892 through to 1921 and then extended it via Shoghi Effendi until 1957.
All the wrirings of Abdul'baha and Shoghi Effendi are taken as authorised interpretations of the Message of the Bab and Baha'u'llah.
So from 1844 to 1957, we had access to the Word given by God.
That is logically great evidence of a very soundly fulfilled prophecy.
Regards Tony