「岂止美满」可以改成「还要更加美满」

Since you are learning both Chinese and English, I am not sure which parts of translation you are asking. Anyway, here are some correction for the use of Chinese collocations: 操办婚姻 -> It would be better to say 包办婚姻, at least in the mainland of China. BTW, speaking of mariages arranged by parents, there is another hillarious practice: 指腹为婚, a marital realtionship is established even before they are born. 一手操办的好事: This sounds sarcastic and implicitly shows that the speaker is a little bit angry. Another similar one in casual conversion is: 瞧瞧你干的好事！(look what you've done!). PS. the usage of 一手 is really a nice shot!

翻译的很好

Let me give it a go. Any corrections or refinements to the translation are welcome. My mother's marriage to my father was a good deed orchestrated entirely and solely by my maternal grandfather. In hindsight today, there was really nothing bad about such an orchestrated marriage. Although my parents were unable to grow old together as a couple, their marriage was far more than tenfold merrier than those free-choice ones in the world that are followed by subsequent fights and quarrels or separations and reunions.

谢谢你的答案