I think in the English, it says the lion cubs are subjected to harsh tests or something.
I imagine the first two symbols have to do with royalty.
"I see. That's strict..."
きびしい - strict
"Brother. You're slow. Speed up a little." (I guess they're using brother as an affectionate term here, and not the biological one.)
おそい - slow
はやく - to speed up
"Huh? I got the wrong path? Let's go back, bro."
I think the character after the space on the second line means path.
もどる - I think this means to return or go back. I've seen it enough times. Not sure how this differs from 帰る though.
I've seen it enough times now, so I think the two characters before the last space on the first line means test. Which means if we go back to a previous screenshot that contained this text, it most likely says children of royalty (they're referring specifically to the lions) like to take tests in this valley.
I wonder if that symbol on the bottom line after the space could mean mercy.
He's basically explaining what a hot spring is. At least I believe that's what those two characters at the beginning of the line are saying.