Dragon Age: The Veilguard brought back jumping from Dragon Age: Inquisition, and made a fair amount of improvements too. For starters, Rook will make an effort to cling onto ledges and put in a bit of extra effort to make longer leaps.
However, it's still far from perfect, prompting one player to do something about it. Nexus user Gabett has released a whole bunch of mods that make the game less frustrating, including some that target traversal. This includes letting Rook run around a little faster, and thankfully, jump higher.
Gabett has released multiple mods which make the game easier to play, like letting you earn XP faster or freely access any skills on the level-up screen, but one of the most popular recent releases improves Rook's jumping. With this mod, you can jump up to twice as far as usual, helping you make leaps you'd otherwise be struggling against.
Then, there's a mod that sounds absolutely perfect for that one part of Arlathan Forest - No Drowning Animation and Walk Underwater. This does exactly as the name suggests, removing the need to avoid any body of water that reaches your shins. For some reason, Rook is so afraid...