I see the following solutions:
1) Use the current script parse-advisory.pl. It may be ugly but it does the
trick in nearly all cases. DSA's are committed automatically and the web
team reads the commit diffs and corrects after the fact if needed.
2) A hybrid approach combining parse-advisory with as much structured
information as is available. dsa2list could be a good starting point.
3) Only use structured information on the website, and link to the
mailinglist for the full text. This has the drawback of missing
translatability but should make it fully automated even without need
for review.