If an entity fails its Charisma check against “Planar Binding”, is it possible for it to unintentionally violate the instructions, or does the magic of the spell make it impossible for this to happen?
Relevant text from spell:
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A bound creature must follow your instructions to the best of its ability. You might command the creature to accompany you on an adventure, to guard a location, or to deliver a message. The creature obeys the letter of your instructions, but if the creature is hostile to you, it strives to twist your words to achieve its own objectives. If the creature carries out your instructions completely before the spell ends, it travels to you to report this fact if you are on the same plane of existence. If you are on a different plane of existence, it returns to the place where you bound it and remains there until the spell ends.
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Suppose the caster has a long list of instructions for the target (see How can an entity bound by Planar Binding be prevented from betraying the caster? for an example).
The spell states “… must follow your instructions to the best of its ability”, which to me implies that it is possible for mistakes to be made (depending on the intelligence of the target, keeping such a list of instructions in mind at all times and being able to see the interactions between competing commands will sometimes be beyond their intellectual abilities in the moment and they may therefore unintentionally violate some instruction at some point). What happens to them if this occurs? Are they wracked with guilt? Do they suffer psychic damage? Are there zero consequences in this situation? Or does something else happen?
Note that this question of what happens to the entity when it unintentionally violates an instruction is different from how the entity experiences “must following your instructions” (see Does the target of "Planar Binding" experience an irresistible compulsion? for that question), but the two questions are interconnected.
One simple explanation for “how” the Planar Binding spell works is to say that the magic forces the entity to comply with the instructions (their free will is removed in any situation where their action is dictated by the instructions). But if that is how the spell works, then it is NOT possible for the creature to unintentionally violate the instructions .. the magic forces them to behave in accordance with the instructions if it is within their ability.
Maybe a different way of asking this question would be “Does the entity need to think through the instructions and figure out how to behave, or can they just act normally and know that the magic of the spell will force them to abide by the instructions”?