Actually, Our World and Your Story are quite clear on this point. Standard magic immunity catch is "immune to mortal magic, not mundane sources of harm", also phrased as "immune only to mortal magic". It's consistent with every character that's demonstrated it in the books, and for that matter, ways of bypassing it, regardless of source, are also consistent in the Dresden Files stories. This is how it is represented in this game, there is no "extra" weakness.
This is by the way, worth a +5 catch - both Madrigal and Lord Talos have magic immunity via magic items, and get a +1 for the item, +5 for the catch cost break on physical immunity. Real Ogres just get the immunity straight up, it costs them only 3 refresh and it has no weaknesses beyond "it isn't mortal magic".
What that catch seems to mean is NOT "all spells fail near you if they cause anything bad to happen, directly or indirectly". It means based on the books "you can not target them with magical energy and have it work, regardless of the shifts you generate. Anything around them, however, is fair game". Another way of thinking about it might be that you can't make a magical connection to them...not with a focus (hair, blood, etc) nor with line of sight a;though that causes issues with the famous Maggie death curse. So I like the former definition better.
Maggie bypassed the catch by using a blood connection to Raith (Harry and Thomas) and explicitly wording the spell so that Lord Raith wasn't the target, but instead the life energies of those he interacted with were the target. Which in a RPG would probably be rules lawyering, but Maggie's player clearly was that kind of person