The proofing tool flattens and converts all uploaded files into a PDF, which loses any of the original source documents features and can also distort / destroy the original documents styling. it also has limitations for any form of web site proofing and markup. While it would take a technical investment it would be greatly beneficial to migrate to a proofing tool that doesn't convert file type on upload but keeps the original format and adds the markup layer on top of it. This would allow for a more true to source proofing as well as increased feature flexibility for websites / emails / dynamic content.