Could it be left to the user to choose which articulations are considered “large enough” to be forced outside the staff with this option? Personally, I would force Schoenberg’s stress marks outside the staff as well.
More importantly, there is no property to override this positioning; not even Offset in Engrave mode. Even if the global setting positioned accents outside the staff, perhaps you find a one-off where it would be clearest to have it inside instead. I would probably set it as an additional property in Articulations, like “Force outside staff”. That way, if there were many notes that needed correction, the articulations could all be forced outside but preserving staff placement above and below.
On the subject of those properties, I’m not sure about the utility of the current Placement options. You can currently force stem side and notehead side, but you cannot force above, below, or natural. With the current implementation, if you have accents placed naturally, but you want to set several notes to have them above, then you must set the downstem notes’ property to “stem side” but the upstem notes’ property to “notehead side”.
In Engraving options, each articulation type has just two Placement options: “Above” and “Natural” (from my understanding, natural is “notehead side if single-voice, stem side if multi-voice”). For more comprehensive articulation placement settings, I propose adding “Below” and separating natural placement into “Notehead side” and “Stem side”, adding the boolean option “Force stem side in multi-voice context”. The four-way “Placement” option, the “Force stem side in multi-voice context” boolean option, and the “Force outside staff” boolean option should be available for each articulation in the Engraving options page, as well as the properties of each articulation for overriding. Something like this mockup:
