Tools -> Convert To -> Welded Bezier . This gets the 4 lines to a closed polygon. Which is good enough to accept fill at least. Change Interaction Level to Scale, ( that is: Format -> Interaction -> Scale in the menus). Then it will behave as a rectangle.
Match Scale: I'm guessing here without exact details: In EazyDraw, on Preferences. Set SVG Pixels to 90 ( could be? 96 is what Intaglio exported ). But this setting needs to match SVG authoring convention. Don't try to fix it with EazyDraw's Scale palette settings - you will be off down a rabbit hole. EazyDraw Help pages explain the SVG issue of 72, 90, and 96 Points per Pixel uncertainty in SVG.
Send EazyDraw Support the SVG with the 4 lines to represent a rectangle. EazyDraw has a post SVG, DXF and PDF conversion pass, the fact that Intaglio degrades the rectangles can be fixed - we just nee one or two good examples to teach the algorithm. - we need exact Intaglio content as this is (most likely) an error on export, there may be legit SVG with 4 line rectangles, so we can't just promote all 4 line boxes to rectangles.