You've got it just about right... Here is a (over)simplified explanation:
Macro contrast is the ability of a lens to render black areas very black and white areas very white. A lens with poor macro contrast will scatter (or flare) light from the bright areas to the dark areas, hence rendering the dark area lighter and the light area darker. In the dark area, there will be no texture present, just a slight density present in the negative where it should be clear (black is reproduced as clear in the negative). The light area is likewise slightly darker due to the flare, because some of the light has been robbed from it and sent into the dark areas of the image.
Micro contrast is the ability of the lens to differentiate between adjacent areas of the image that differ only very slightly from one another in contrast - hence rendering very fine textural detail in both the highlight and shadow areas of the image. Due to excessive flare, poor macro contrast can thus adversly affect micro contrast as well as creating the aforementioned problems in an image.