In writing the document, I noticed that the summary tables often have the same role names ("Party", "Party") but the activity diagrams use different roles ("Party", "CounterParty"). It might be clearer to have distinct roles in the summary tables that match the values in the activity diagram. (Other standards, such as UBL, do this in a similar way). If messages can go in either direction, the table should have a two rows for the two situations.
The activity diagram in 7.5.1.1 has "Party" in both swimlanes, this could be changed to "Party", "CounterParty" as in the other diagrams for consistency.