Avengers: Endgame wasn't the original title for the movie. The Russo Brothers had another title in the running for quite some time, and even that one leaked out ahead of time. After Infinity War hit theaters, Marvel Cinematic Universe fans were desperate to learn the title of the follow up, but the Russo Brothers and Marvel Studios boss Kevin Feige admitted it was going to be a while before it was officially revealed, which nearly blew up in their faces as they underestimated the demand. Feige admitted as much when he revealed he was worried about fan response to the title reveal.
When talking about Avengers: Endgame and the title, Joe Russo said, "Well, it was Infinity Gauntlet for a long time." Both Infinity War and Infinity Gauntlet borrow their titles from Jim Starlin's comics and the sequel title was one of the first ones MCU fans guessed about, since it was logical. However, even when the title was Infinity Gauntlet, the directors were misleading fans telling them that the title had not been revealed yet. They did the same thing with Endgame.
Zoe Saldana actually revealed the Infinity Gauntlet title back in 2017, but it wasn't really picked up on at the time since Infinity War wasn't out in theaters yet. As for Avengers: Endgame, the title was mentioned by Doctor Strange in the last movie as he mentions it to Tony Stark on Titan. However, the title seemed to have had different meanings in different countries. Anthony Russo explains.
"When we went to Korea to promote this movie, the representatives from Disney there came up to us and said, 'Um, there's something we need to tell you. In the translation of Infinity War here in Korea, when Doctor Strange says to Tony, 'We're in the endgame now,' the way we translated that here was 'no hope.' So we're like, 'Oh, so I guess in Korea, is this movie called 'Avengers: No Hope?'"
No hope isn't a terrible title for Avengers: Endgame and it's pretty much where Earth's Mightiest Heroes were at the beginning of the movie. Fans were the same way when seeing the promotional material for the movie after watching Infinity War. There wasn't a whole lot of hope to go around. Even after the conclusion of Endgame, there still isn't a whole lot of hope, though there is more than there was before.
Avengers: Endgame is probably the best title the Russo Brothers could have chosen for the movie. It is the end for a lot of characters and it's setting up the events for the MCU's Phase 4, which will officially launch after this summer's Spider-Man: Far From Home. Hopefully we'll get a tease of what to expect in a post-credit scene from the highly anticipated sequel or at this summer's San Diego Comic-Con. The interview with the Russo Brothers was originally conducted by the Happy Sad Confused Podcast.