I've seen you use this on multpile edits (on multiple wikis) so I'll just cover all of them here:
"John Stewart permanently sealed the portal" is the simple past. It's correct grammar for this sentence.
**"John Stewart have permanently sealed the portal" is the present perfect. It's wrong on multiple ways.
First off, "have" is only used for first and second person. It should be at least **"John Stewart has".
Present perfect is a present tense. But the entire section is in past tense. The shift in tense in incorrect. In past perfect it would be "John Stewart had sealed".
Simple past is better than past perfect. The past perfect denotes an event that happened in the "past of the past", so before the point describes. But the history section does cover everything in a chronological order, so that's not the case here.