Okay, then let’s take a step back and see the Haiku user not as a tourist but as a human being with a functioning brain and the natural curiosity that everyone is equipped with.
You make it sound like once everything in the OS is localized, the user will have no problems at all using Haiku, even if it’s the first time he/she enters this environment that will always be different to other operating systems.
I mean: the same level of intelligence + curiosity needed to overcome those differences in functionality and the way they are presented (and/or set up) will also be needed to deal with the language differences for the parts of the OS that we’re talking about.
Are you then also going to state that you cannot for example “force” a user to learn even a few differences in functionality from what he/she is used to? What would he/she be used to? It can be anything. Windows, because most people use it? Doesn’t cover each case, and how can you be sure?
Remember the brain and subsequent natural learing capability that every human capable of using a PC has. Learning capability that cannot be separated from curiosity. This curiosity to try a different OS will always include an amount of goodwill, which means the new aspects are unlikely to be experienced as something that’s forced upon that user.
Plus (going back to the tourist metaphor), Haiku has documentation that I believe is localized and provides short descriptions in the local language. There’s a tourist guide after all, so to say.
A third help comes in the form of icons that are not guaranteed to give a clear understanding, but will help in most cases.