Create a tag set with 20+ characters and relationships each.
Create a challenge using that set
Sign up for the challenge
on the /collections/$COLLECTION/signups/new page, click on "Show Characters" then "Show Relationships"
If "lucky", the cache kicks in and either "Show Characters" will show the relationships, or vice versa.
Even if the correct type of tags shows, the tags in it may be wrong (especially if wrangling, not edits to the tag set, has changed the tags).
There is also a fandoms version of this page, e.g. http://archiveofourown.org/tag_sets/show_options?restriction=10986&tag_type=fandom
Make sure the Show Characters/Relationships/Fandoms pages show the right kind of tags.
After visiting the Show Characters/Relationships/Fandoms page, try modifying the tags in the tag set, and making sure the page updates.
After visiting the Show Characters/Relationships/Fandoms page, as a wrangler, try editing the diacritics or suffix of a tag in the tag set and checking if the page updates.