It's consistent through The Empress, I just gave an example. But maybe it's a decision specifically for this show?
For example, when Elisabeth is practicing several languages, each is subtitled "[in $language]", but when she switches back to German the subtitles readily explain... "[in English]". This confused the hell out of me!
It did remind me of watching "The Beast" (La Bête)[0] in the original French with subtitles and I was then surprised when I saw the subtitles say "[In English]" and I was, "Oh, damn, the characters did actually switch to English".
[0] https://en.wikipedia.org/wiki/The_Beast_(2023_film)