The wording in my FCOM (in English) is almost identical to that. Here is what I was getting at with the dry snow/accumulation thing:
Copied/pasted from my Deice manual:
...3. In very cold conditions (generally below -10 to -15°C (14 to 5°F) or colder) dry snow can fall onto cold aircraft wings. Under these conditions, dry snow will swirl as it blows across the wings, making it evident the snow is not adhering. But if snow has accumulated on the surface of the wings it has to be removed prior to takeoff. It cannot be assumed that accumulations of snow will blow off during takeoff
NOTE: An accumulation is any amount of snow beneath which defined
markings (decals, paint stripes, rivets, etc.) cannot be observed.
Not much room for interpretation there.