Well-detailed social adventure, a refreshing and interesting change for being solely in polite society. The mystery isn't too complex, but the layers of society between a stranger and the crime scenes read like it would be a good roleplay challenge.
Elegantly formatted, though a few more boxes and lines would help separate sections cleanly.
A handful of sentence fragments scattered throughout.
It would be helpful to state that the NPC Sources are your other adventures available on Itch, if you are referring to them as sourcebooks.
As far as things to cut - it's been mentioned below, but throughout the whole doument there is a lot of text, single sentences and clauses, that doesn't need to be included - suggestions to ignore X or Y, verbose-yet-vague descriptions, etc.