::: Firstly, it must be noted that there has been compromise, and that several of the suggestions have been incorporated. 

 As to the remainder, the overriding problem is the casual language. Fragments such as: 

 "Louis narrates how he reached this point" is clunky and less formal than the more appropriate In a  flashback, Louis reveals in narration the circumstances of his imprisonment. 

 This is minor, but Louis' mother is forced to take a boarder - more accurate than "humbles herself" which is also clunky. 

 "Unimpressed by his prospects, Sibella turns down his proposal and instead marries Lionel (John Penrose)" is firstly an assumption and casual (ie. "turns down"). This: After being rebuked by an now adult Sibella and witnessing her marriage to Lionel (John Penrose) is more formal and 100% accurate. 

 "At his workplace, Louis has to wait upon" is clumsy, but there can be a modification that incorporates the best of both.  "A darkroom explosion makes her a widow" is simply unnecessary and casual in tone. This can also be modified. You've also missed the viewing of the remaining family at the church. 

 That said, there are some improvements, such as the fatal boating accident and the letter of condolence.