While Chris is correct about the poor anti-halation properties of Foma films, what you are describing and what I am seeing has nothing to do with that. When a film halates it causes diffuse halos around highlights because the light is scattering and reflecting off of the film plate. This is a property of the film regardless of what developer you use. HIE was infamous for it.
What is happening with your negatives is a result of your stand development. Rodinal is a fantastic developer, but the use of it as a stand developer is problematic. Without getting too technical, because of it's high pH Rodinal in effect stays active along the contrast edges of a negative. The fresh developer in the shadow tones along these edges diffuses into the adjacent area and increases the density of these areas resulting in an effect akin to an unsharp mask in Photoshop. Without agitation this mechanism can get very pronounced and this is why you are seeing the halo. It tends to occur more in thicker traditional emulsion films.
Talk to people that have decades of experience with Rodinal (ahem) and you will find that stand developing isn't a good use of the developer. Neither is using it in really high dilutions for other reasons unless you are doing rotary processing. I am not saying that it doesn't work, but it is more difficult to obtain optimum negatives this way consistently. But you know that now firsthand.
If you are hell bent on stand developing the use of lower pH Glycin developers works far better. Fx-2 comes to mind which was developed by Crawley partly for the purpose of stand developing. The only good or famous photographer that used stand developing that I am aware of was William Mortenson. I don't recall what developer he used but I wouldn't doubt it is on the internet somewhere and I wouldn't be surprised if it contained Glycin. I would almost expect it to contain Glycin.
