As an FYI: the main Altium site now has a web-based online viewer (including schematics). If one digs far enough through the iframe & network calls you'll discover that the schematic content is converted on some backend server and then returned as SVG files.
This might be a useful source of "ground truth" for comparison purposes.
(It appears this functionality results from the Upverter acquisition.)
Feel free to close this issue after you've read it.