In the original game, the map edges were a clear, defined line. I feel like it's kind of an exploit to be able to hide units (chinooks carrying tanyas) in that thin line of perma-shroud and move about the map. I'm not sure how the mod works, so I don't know if fixing or improving that somehow is possible... or if it's even desired by the dev team.
Having played Supreme Commander before, I'm familiar with people skirting map edges to get around unseen, so I can adapt. If it could be fixed somehow though, it'd be appreciated.
I would recommend going in to the options and enabling health bars or whatever they are called, this will make it much easier to notice any sneaking units since you will see a bright health bar.
I also saw this while playing against the AI in the original Dune 2000 where it sneaked an engineer running on the top edge of the shroud hardly visible into my base. This is an annoyance inherited from the original. Not sure how to solve this best.