At a large scale of spreading, or in the long run, yes, there may be impacts.
First of all you should answer a question - why would you sow seeds in the wild? If it was solely in order to increase the availability of the plant, then you might care that the seeds will thrive and nothing else, but at the expense of an ecosystem.
If what you want is to help the plant integrate in a new area, or to re-establish it in an area from where it disappeared, then you have to consider many things. First, seeing if the environment fits the plant's needs, and second, finding out the chances for the species to be invasive. And that's completely relative, a species that might act as invasive in one area will find an available niche in another.
Acacias are a prosperous and old group, they are tough and they know how to thrive. In South Africa they have used seed-eating insects to control the spread of a few australian acacias.
If you know what you're doing, spreading seeds or plants in the wild sounds like a good thing. But if the idea is sustainability in the long run, growing yourself is the way to go imo. Acacias will do fine in the wild, as long as people does not kill them.
"The Menu is Not The Meal." - Alan Watts