For custom taxonomy - yes, the links are like this indeed.
(well, at least site.com/?customposttype=%postname% and site.com/?my_taxo=%taxo_name%)
But for built-in posts pages, categories and tags - no: you have either
or the folder-like
And for some plugins extending content querying possibilities, and therefore working only with the parametric addressing, not with the folder-like, using slugs as parameters of canonical (base) links would be more optimal, than using IDs.
Oh, and one more feature request: in page editor, you can easily delete the dependencies by deleting assigned terms in respective language-id fields. In category/tag/taxonomy editor, once you assign a corresponding term in another language, you are stuck. If you have made a mistake, you must delete the term, because you cannot undo ("edit" takes you to editing another language term, not to changing which term of another language should be assigned to this one).
Anyway, you have seen the website I'm building for a friend of mine: I am facing the problem of dissapearing posts (custom type), I have no idea how can I debug it (when and how were the data removed from the DB, but when I exported data to CSV, the data we were filling for days are gone from db only after displaying the webpages = switching the language a few times) and must now decide a fail-safe simplification (which plugin to exclude)
What I wanted to achieve was storing price-factors in taxonomy fields, to be able to calculate the service price by multiplying the factors of all terms describing the service. I may give up the custom taxonomies, but I still need to add the fields to categories and tag terms with some plugin.
So, I can delete Custom Post Type Permalinks & Taxonomic SEO Permalink plugins, but I think, I must leave Ultimate Taxonomy Manager.
I am very thankful, Chouby for your presence and active support.
But as a fresh WordPress implementer, I'm already a bit frustrated, as the forums seem not to be as much-attended (or topics I'm stuggling with do not gain much attention) and if the compatilibity is such on an issue, maybe such questions, concern the WordPress plugin/theme model generally...? Greetings & thanks if anyone has any hints.