I noticed the chapters Lonely Journey and Lone Journey II weren't adapted into anime episodes. What's up with that? Gildarts didn't appear in the anime since the beginning of the Grand Magic Games arc in Series 1. If Gildarts joins the battle in the Alvarez Empire arc and the anime is ignoring the Lone Journey chapters, then it'll probably be a while before we see him in the Series 2 anime.
"Lonely Journey" could've been adapted in the episode "The Dragon King", after the intro and before the Bar Sun scene. I know the chapter didn't have dialogue but the anime guys could've written some in. Like, say Gildarts talks to the bar tender to kind of recap what already happened. Then Gildarts would say what the guild stands for and the Bar Sun scene would then either contradict his words or prove them.
After the anime completes the "Tenrou Jade" arc, they should start the "Challenger" episode with "Lone Journey II" and, again, add dialogue to it. When Natsu tells Gildarts what's on his mind, he would recap what happened in the Tartaros arc. The scene would end a different way with Natsu pushing Gildarts even further back than their first encounter. Natsu would then say "I'm fired up now" before the two charge at each other. Then we'd cut to black, reading "One Year Later" then opens with "Challenger".