Should request receipt and loading-area availability be separate interface events?

I have put both interpretations of ready on our UR5e spacer-loading sequence. The machine supplier means it has received the request. The integrator means the loading area is available. In our example, receipt can happen while the machine is still finishing its work, so these cannot be the same transition. Is a sequence walkthrough with that example the clearest way to get the two teams to agree their interface?