When I don't immediately vote to accept your house rule, it is because I am deep-rootedly sceptical to all quick fixes to complex rules.
I really like the idea of weak items fizzling in strong opposed auras. For narrative effect, I'd probably prefer the light from your enchanted lantern to dim rather than go out, but the idea of auras having a MR towards opposing realms is good, I think.
I suggested in our saga to ASG that it was to be reduced, for charged item, to 1 = 1.
It will reduce the "magi having 1 item with 100+ pén for those enemies they cannot beat using spells, but not having invested vis into talisman/invested/lesser item which are costly and destructible where a charged item destruction is just a non-event" (because in one season, my players create easily more than 10 charges and do only take 4-5 charges with them, for "bosses"' fight)
Also, in our saga, spells to target magi's worn items are common and often used before any other offensive spell. Against those, only a talisman is really effective (because parma); other items fall on the ground, broken. With charged item, the sheer number of them may mean that the spell destroy X charges (put in X items) but you wore more on you than the PeTe (or whatever, or with casting requiste if needed) spell targeted. And MR against those spells has been by consequence a must-have. Thief and cop.