When editing tag wikis, you're limited to one edit per 30 seconds (see the rate limiting guide). However, the displayed message is slightly confusing:
You can perform this action again in 30 seconds.
That's wrong; you don't have to wait 30 seconds, it just needs to be at least 30 seconds after the previous edit. It should either be
You can perform this action again in x seconds.
(where x is the appropriate value)
or something like
You can only make changes to tag wikis once every 30 seconds.
(both 'styles' appear in different rate-limiting messages, I don't have a preference).