Add language prefix to permalinks

I”m not sure if this is the “best” way to approach it but this is what I would try first.

I would create a taxonomy (like categories) called languages. Maybe even use categories (if they are not in use for something else). You can structure permalinks to go example.com/<cat-name>/<page-stub> and, thus, have the language as part of the URL. I would imagine you can do the same for a custom taxonomy.

This would allow you to have separate archives for each language.

You can use register taxonomy to make a new category-like or tag-like taxonomy.