If you change the instrument language in Engrave > Engraving Options > Language before adding instruments, the name shown in the top left of parts should be in the correct language automatically. When you add an instrument, that name is used for the player name, and in turn, is also used as the layout name. If you rename the player, the layout name gets updated automatically. However, if you change the layout name, any subsequent changes you make to the player name no longer affect the layout name (like a page override).
Likewise, if you change the language after adding instruments but later then reset instrument names, as long as you haven’t changed either the player or layout names manually, both should update when you reset the instrument names. (If not, you can also reset them using the arrow in the name field when you double-click the player/layout card.)
You can also save the current state of engraving options (including your language setting) as the default for all future projects.