Here's a definition from Brooks Brothers site:
An unstructured sport coat, also referred to as a “unconstructed,” “deconstructed,” or “soft” jacket, is precisely that: a jacket with less structure. Unlike traditional jackets, an unstructured sport coat will have a soft shoulder, no internal canvas, and usually will have no lining other than along the shoulder and through the sleeves. Put one on—you’ll feel the difference immediately.
So by definition if it is fused or canvassed it is not an "unconstructed" jacket.