Hey there @Golaxo,
You put your finger on the issue here. The standard user roles in Wordpress are not translatable to Discourse: “editor”, “contributor”, etc don’t mean the same thing in Discourse as they do in Wordpress. There isn’t a use case that calls for this kind of “role” translation, and I don’t think that’s what you’re after either (but please correct me if I’m wrong).
What you’re after is a Discourse groups sync for a specific provider, namely WooCommerce. As you alluded, there’s a solution for that here
The reason there isn’t a “generic” version of this in the WP Discourse plugin itself is because each Wordpress plugin that provides a “groups” feature does so in different ways. The way WooCommerce handles groups is different from how other Wordpress plugins do it.
But if you’re having issues with the WooCommerce membership sync you could always ask me about that in that topic 