Fun fact: the trees was an reused asset from Lola and Virginia (Myriam's previous series) and can later be seen in the series.
So I've found two backgrounds of the 2005 Pilot of Sandra the Fairytale Detective which was an environment test from an unknown artist but can be seen in CSVisualDesign Proof: https://www.csvisualdesign.com/2d-animation.html?utm_source=chatgpt.com