The seed pods on your plant are very long and narrow with many seeds, very unlike those of Acacia angustissima so I would discount that. The long narrow seed pods may help to identify it, I went through the list you gave on tropicos but couldn't find a match which is thornless.
There are several yellow Impatiens, a closer shot of the flowers may help, also climatic conditions and location it's growing in as many Impatiens prefer cool, damp and shady locations.
