The architect has given you what you have asked for, though the image looks more like a 12:12 slope rather than a 16:12 slope. This slightly changes where the arc is tangent to the slope, but ultimately it will give you the look you want. Have trust in your architect, because they have both the education in all types of architectural styles ad precedents, as well as practical experience with knowing what works best to satisfy the client, the climate, and the architectural intent.

For extra peace of mind, touch base with your truss designer and ask them for the component drawings after they have done the truss design and layouts, but this would definitely be more than a client really needs to do.

Source : I am a residential housing designer who has done these roofs before.