Gosh. That's really lovely. Beyond my current capability level. I noticed that site has a section for readers to share errors they found in patterns. Gosh, some are fairly substantial so it seems!! Perhaps if you contact the company they may let you speak to the person who made that garment up for them and you could ask for any special advice etc they could offer??
I'd also love to see how you fare with this item. Some nice patterns on that site.
I looked again at that site and through the main contact there is a forum. Sorry, I dropped out the browser page before sensibly taking the url but the forum seems to be the place you can ask the CEO/designer questions.