wpgraft never reads WPBakery’s data. There is no exporter, no importer and no shortcode translator anywhere in this, by design, because those are the parts that break. wpgraft reads the page as your browser rendered it: the real elements and the real computed styles on each one, at every breakpoint you ask for. It then rebuilds that as Elementor’s own native elements, with the styles written into Elementor’s own fields. Nothing that arrives depends on WPBakery still existing.
Moving off WPBakery normally means rebuilding every page by hand, because there is no honest path from vc_row shortcodes to Elementor’s widgets. wpgraft does not try to find one. It reads the page WPBakery rendered and rebuilds it as Elementor’s own elements, so the design survives and the shortcodes do not come with it.