how is your frog setup, is it a pawn or a character?
using the launch node probably isnt the best method, to my knowledge it doesnt take into account the nav mesh at all as its more of a physics base thing.
you may want to try getting a location vector say 200units forward from where the frog is then use the project point to navigation node to ensure that where your moving to is within the navigation then use a timeline to move the character. you could also try using the move to node for the movement and making the character jump at the same time (this wont give you as much control or be as accurate though).