eum = "a man/one", ut opinor
eum repetendum, "as someone who should be recalled", I think
"While it indeed was successful, nevertheless I consider myself, who subsequently was in the greatest positions of power, as one [/a man] who, should he be[/were he] recalled as such [i.e., a quaestor], would not garner that much glory from praise due the quaestorship."
I'm writing in Latin hoping for correction, and not because I'm confident in how I express myself. Latinè scribo ut ab omnibus corrigar, non quod confidenter me exprimam.