Hmmm, I’m just trying to get my head round what you have described.
Anyway. The way I understand it. You have a menu or a link somewhere in your main site with the label international. You also have a languages folder with 18 documents, 6 for each language (english, russian, chinese), right? And you want the menus for these language pages to be different depending on the language chosen, right?
I’m sure there’s different ways of doing this. Here’s my 2 cents:
A visitor comes to your site and clicks on "international". They are taken to a landing page with say, 3 flags or other images one for each language. If I click on chinese, I should be taken to another page in chinese. I suppose this chinese page (and the other languages too) have a page that will act as their landing page, right?. If this is the case, then, what I would do is that on that landing page, chinese in this case, I will have a Wayfinder call and use the &includeDocs filter parameter to exclude the 12 "other language" documents from the output (using their doc ids) and only include the chinese documents you want. E.g. &includeDocs=`8,56,81,80,12,83`.
I will do the same for the english and russian landing pages. Only difference between the 3 Wayfinder calls would be the docs that are included.
I hope this is what you were after?
&includeDocs
default: 0
values: [ comma-delimited list of document ids ]
description: Acts as a filter and will limit the output to only the documents specified in this parameter.
The startId is still required..