wpgraft never reads Elementor’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 Bricks’s own native elements, with the styles written into Bricks’s own fields. Nothing that arrives depends on Elementor still existing.
This is the most-asked move in the WordPress builder world, and it is normally the most painful, because Elementor and Bricks have nothing in common at the data level: an Elementor widget and a Bricks element are different objects with different settings, so there is no faithful mapping from one store to the other. wpgraft sidesteps the problem entirely by never looking at Elementor’s data. It reads the page Elementor rendered and rebuilds it as Bricks elements with Bricks global classes, which is the thing you would have built by hand.