Nothing is mentioned in the descriptions of the traits, true, but at the same time they are traits exclusively found on ranged weapons. So it´s not really weird that they do not start of melee attacks even if those melee attacks are made with a weapon nominally made for throwing.
Plus it would probably be too strong if they didnt have that restriction.
I’ve queried this, and it’s working as intended. You’re correct that it isn’t specified that it needs to be ranged attacks, but it does have to be ranged attacks.
I’ve passed this on and suggested the description be updated to be clearer perhaps.