This is part of what makes distributed systems so much more complex than non-distributed systems: once you have done the 200/202 response you are then responsible for the handling and if you haven't communicated back a way for them to find out what happened to it you can't expect them to do anything differently unless it is part of a negotiated protocol.
Trying to solve this is ultimately how we get things like the FLP result and the PACELC theorem.