Here the word "we" refers to Peter and the other apostles, but not to his readers. AT: "For we apostles did not follow cleverly made-up stories" (See: [[rc://en/ta/man/translate/figs-exclusive]])
These two phrases may refer to the same thing and be translated as a single phrase. AT: "the powerful coming" (See: [[rc://en/ta/man/translate/figs-hendiadys]])
This can be stated in active form. AT: "when he heard a voice come from the Majestic Glory" or "when he heard the voice of the Majestic Glory speak to him" or "when the Majestic Glory spoke to him" (See: [[rc://en/ta/man/translate/figs-activepassive]])
Peter refers to God in terms of his glory. This is a euphemism that avoids using God's name, out of reverence for him. AT: "God, the Supreme Glory, saying" (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-euphemism]])
With the word "We," Peter is referring to himself and to the disciples James and John, who heard the voice of God. AT: "We ourselves heard this voice that came from heaven" (See: [[rc://en/ta/man/translate/figs-exclusive]])
# heard this voice brought from heaven
"heard the voice of the one who spoke from heaven"