Contrary to this, if the target's mom that has died years ago suddenly appears in front of it, the target would probably "resist" the illusion and investigate it (as an action, after it failed the initial INT saving throw). Consider, that illusions that look like magical spell effects are hardly "not reasonable", because the target would normally think that it's a "normal" spell effect. If the illusion is not reasonable to the target, it will probably investigate it.The object must be visible for the target (spell description).That is very different to other illusion spells. Physical interactions do NOT reveal the illusion! The reason again is that the illusion is within the target's mind.Consider that only the "conjured" creature must be not larger than 10 foot, but not the area that it is able to move within. The reason is, that the creature is within the target's mind, so it won't be stuck to a position. Instead, it would also follow the target, if that is trying to escape, etc.
Analogous to that, if you create a hostile creature that is attacking the target, this creature would not be bound to its position.Like Jeremy Crawford approved, created objects will move with the target and can also cause status effects ( see his Tweet here).And those can even cause status effects (e.g. Furthermore this is not part of the spell's description, although some other spells explicitly say so. That's part of why they're just single-target.". So, it relies on the target's sense of what's possible, not the illusionist's. Like I'm a Banana said, "It's not like the illusionist is making the illusion say something, it's like the illusionist is saying, "get this concept across" and the target's mind shows the target what the concept would look like from the target's perspective. If you create a person, you do not need to know the language/appearance of the it.These are just the main agreements of this discussion: Phantasmal Force is very vague and this thread was a try to find an interpretation that is consistent with the wording of the RAW and that is consistent in analogy to other spells. Please note, that I don't claim this to be the only way of interpreting the rules. EDIT: The following is a personal summary of this forum thread: