Hello Florian,
I was reading your article, Would you mind if I asked some advice.

When I update a product using the API with the attribute term that includes a space e.g "Brand 1, Brand 2", it creates three attributes for me, "Brand" , "2" and "1". What am I doing wrong. Single attributes are fine.

I send it to woocommerce the following

  [3] => Array
        (
            [id] => 2
            [name] => brands
            [visible] => 1
            [variation] => 1
            [options] => Brand 1,Brand 2
        )

and it does this.

  [attributes] => Array
        (
            [0] => stdClass Object
                (
                    [id] => 2
                    [name] => brands
                    [position] => 0
                    [visible] => 1
                    [variation] => 1
                    [options] => Array
                        (
                            [0] => 1
                            [1] => 2
                            [2] => Brand
                        )
                )