Hey Dude,
i have the some problem.
URLs for product detail pages like this: {{ category.name |lower }}/{{ product.translated.name |lower}}-{{ product.productNumber |lower}} dont work.
The variable {{ category.name }} isnt avaible for products.
I have only one category in my webshop, so I have set the URL statically: YOUR-STATIC-CATEGORY-NAME/{{ product.translated.name |lower}}-{{ product.productNumber |lower}}
PS: Maybe this will be help you {% for part in product.mainCategory.breadcrumb %}{{ part |lower}}/{% endfor %}/{{ product.translated.name |lower}}-{{ product.productNumber |lower}}/