One error I found in SVG import was files that contains an id that start with a number. Simple solution for this is to replace any id entries that start with a number e.g. id="1" with id="_1" in the onload event
svg = svg.replace(/id="([0-9]*?)"/g, 'id="_$1"');
The other problem is an svg that contains text. To display corectly, access to the font file that was used is needed. I import the svg to a group an then iterate thought the children and the font in any text items to one that I have present on the system.