In part 9 (v1.05.03), the different methods provide no truly adapted StatusCode when an EventId is not valid to execute the method even if it is known.
AddComment: in case the server does not manage branches, it seems that only the latest EventId should be accepted to write a comment since it is the only case that will allow to write the Comment variable node. In all other cases where EventId are known but not valid the proposed result codes of Table 18, as Bad_EventIdUnknown, does not seem adapted.
Acknowledge: if the AckedState was never acknowledged and no branch is managed by server, or the EventId is known but refers to a state where AckedState is not defined (NULL). The same issue on choice of result code is encountered regarding codes of table 37.
Confirm: same issue than for Acknowledge regarding code of table 40.

For the reasons indicated above, it should be interesting to add other possible result code in the tables of those methods:
add a new status code Bad_EventIdInvalid or use existing Bad_InvalidState status code if the transition or treatment is not possible for another reason as Bad_ConditionBranchAlreadyAcked/Confirmed.