I agree, it is a good idea to select some names and stick to them. It makes it easier to write documents and reduces confusion. I would suggests that the most important step is deciding to use specific names, which names you actually pick are unimportant (so long as everyone knows what you mean)

In one of my software systems we refer to:

• The "End User" who actually does the work
• The "Architect" who designs how bits go together
• The "Builder" who codes each bit

It sounds like your system won't quite match but this suits our way of working.

Another trick I have seen (but don't use myself) is to always mark out the name (say in italics) to remind readers that you are talking about a specific role when you use the name.