I live in the Netherlands, but I speak English and therefore set the language of Roon to English. I also have a Qobuz account that is set to English.
Most of the time the Roon interface is in English, but sometimes it switches to Dutch. For example, the description of the Flaming Lips is entirely in Dutch regardless of whether I land there through my own library or Qobuz.
The Qobuz interface, however, is mostly in Dutch, including the menus and genre selections. However, the Qobuz app (on the same device that I run the Roon client) is entirely in English.
My expectation is that Roon (and Qobuz) respect my language preferences, but it seems that this setting only affects the local Roon interface; everything that is fetched from the internet that exists in Dutch is served in Dutch based on my IP address. (Also, sometimes German because I live close to the border and that happens to anything that uses a GeoIP service to select language, for example, Google.)