With the latest ZeroNet update, cross-site file requests are now once again supported. This time requiring permissions from the user. So I quickly got to work and Kaffiene has become the first site using this new feature. Simply visit the site like normal, grant it permission to read from ZeroWiki, and the info box should work as normal.
Given this is a new feature, all the bugs/kinks may not be worked out yet. Please let me know if something goes wrong! Cross-site indexes will be back soon.