Hey there @DL33,
Thanks for searching for the answer you need here!
Spotify works hard to constantly add music to its content database. However, keep in mind that content availability can vary over time and between countries, depending on agreements between Spotify and rights holders, such as artists or record labels. This might be the reason you can't see some of Patricia Kaas' albums on Spotify.
We add new content to Spotify every day, so if you can’t find something you’re looking for right now, it may appear (or reappear) soon. Alternatively, you can always contact the artist or record label with your query as well.
Hope this helps. Let us know if you have any more questions.