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From the wiki: "For performance reasons, they only apply to playable characters (counts or above). As they are evaluated every day for every landed character in existence, these are very resource intensive."
As noted in that quote, it's actually a bad idea to use triggered modifiers, because of their impact on performance. Usually, my workaround is to use hidden events which apply/remove the modifier based on relevant on_actions (even the yearly tick is often good enough).