After all, he’s not really one to preach the dangers of time travel to his daughter when they both literally went back in time together in the 100th episode and probably altered the timeline.
As for other unexplained mysteries that will probably be addressed in this episode, why isn’t Barry going back in time?
One would think if Iris was in danger of being killed by Cicada, he’d travel back and time and stop that regardless of the consequences.
The Flash 5x14 Promo "Cause and XS" (HD) Season 5 Episode 14 Promo