If the integration with Scroll Translations is enabled in a viewport, the viewport page URLs are always created using the original language's page titles.
From the technical side there is no need for the current behaviour.
We should allow users to toggle this behaviour as there are good reasons for both approaches.
This could for example be done using a check box in the viewport admin screen or through an advanced plugin setting (per space).
keeping the translated page title is useful for page tracking / analytics. What should be improved is the handling of the viewport redirection macro which is not language sensitive & always links to the main language. This should be language independent.