Fusion export proportions are off:
Stroke weights are sometimes interpreted incorrectly in inkscape. Resulting in massively thick strokes that make the file render incorrectly.
To quickly check the file click: view>display mode>outine
This temporarily hides strokes and fills, displaying the actual shapes Origin uses. If this view looks correct, select all the shapes and assign a 0.01" stroke width: Object>fill and stroke>stroke style: width
You can return to the fill / stoke rendered view by selecting view>display mode>normal
things should then look as expected.
Scale is incorrect.
While SVG files can be defined in real world units ( mm, inch, etc.. ) some vector editing applications (illustrator for example ) convert these units to px ( pixels ) Unfortunately assumed pixel density differs between applications,
illustrator assumes 72 pixels per inch
inkscape assumes 96 pixels per inch
corel assumes _______
When opening SVG's in inkscape that were created in illustrator the easiest technique to resolve scale is to click:
File>document properties>display units = inches
Then scale = 72 pixels per inch.
you are then free to select the units you wish to work in.