The switch from Spark to Express URLs automatically redirects old URLs to new ones. However, internal links/URLs do not automatically convert, so that contents lists open new web pages rather than quickly scrolling down the already opened page.

The only way to correct this has been to manually change all the internal links. I've done this in this page, e.g., https://bit.ly/unfurl4a.

A tool to make these changes would have been handy. Failing that, a tool to create and update contents lists automatically, would be a great tool.