Question about the multi-dimensional content model

I’ve revised the example project:

git clone --single-branch -b hugo-forum-topic-56516 https://github.com/jmooring/hugo-testing hugo-forum-topic-56516
cd hugo-forum-topic-56516
hugo server

This is the content structure with the home page and posts section unversioned:

content structure
content/
├── unversioned/
│   ├── posts/
│   │   ├── _index.md
│   │   ├── post-1.md
│   │   └── post-2.md
│   └── _index.md
├── v0.1.0/
│   └── docs/
│       ├── functions/
│       │   ├── _index.md
│       │   ├── average.md
│       │   └── mean.md
│       └── _index.md
├── v0.2.0/
│   └── docs/
│       └── functions/
│           ├── mean.md
│           └── variance.md
├── v0.3.0/
│   └── docs/
│       └── functions/
│           ├── average.md
│           ├── standard-deviation.md
│           └── variance.md
└── v0.4.0/
    └── docs/
        └── functions/
            └── median.md

And this is the mount for the unversioned content:

project config
module.mounts]]
  source = 'content/unversioned'
  target = 'content'
  [module.mounts.sites]
    [module.mounts.sites.matrix]
      versions = '**'

Given that each unique combination of language, version, and role is its own site, you cannot control the publishing path with a permalinks setup in your project config. You could set the url in front matter for each page of the unversioned content, but that means those pages will be written multiple times (e.g., run hugo --printPathWarnings).