[Resolved] Attribute labels translation doesn't work, mixes data between different attributes

Background of the issue:
I am trying to translate the labels for 3 different attributes from DE to FR and EN.

Symptoms:
Labels of other attributes and in wrong languages. For example, 'Couleur' in FR when it actually should be 'Herstellerfarbe' in DE. Or a FR translation of another attribute shows up as the EN label. It's all over the place.

Questions:
Why are the attribute labels mixing data between different attributes?
How can I ensure the labels show in the correct language?