Martin, welcome to the forum!!
an interesting endeavor you have in front of you..
everytime the japanese garden has jumped through geographic growing zones, the garden has adapted and marginally evolved. i think a maltese japanese garden would be of considerable interest, if only for the list of plants you will adapt to suit your desires.
And at each turn I find that there are differing perceptions of what the gardens typologies are understood as. And this is logical as all people see different things in any one thing commonly shown to all. as a result, i would appreciate seeing some examples of what you feel the style is, of the japanese tea garden. If you explain your understanding and perception then I will be able to understand why this mixing of uses may be 'a tall order' . edzard