It's been a while from my Google search that these two spells were discussed.
I know illusions still have a good bit of gm interpretation in them but figured I'd ask
Object has a 20ft burst. Does that mean you could create something that can move around but only within that burst,. What about a "sword of ultimate power* with a level 2 illusory object? Could an enemy pick it up and try to hit me with it? Obviously it would not do damage.
What constitutes an object? A waterfall in the example is a pretty big complex thing with a channel, a mouth, rushing water, etc. Would a maze be an object or multiple objects? What about a chair then? It's made of multiple pieces of wood and a maze is multiple pieces of wall.
How would you run an intelligent group of enemies against it? Would every creature have to seek/interact with a wall to see/walk through it?
What happens when one of the enemies passes the check and audibly tells them that it's fake? Do they all get a free check with no action? I'd assume those that failed could easily retry.
Illusory creature, it doesn't state what kind of strike. Could it be an arrow?
It has no movement speed but it has a range. Illusory creature as a high level monk running at 200+ feet?
What happens when it hits a creature? Does that count as an interaction for the enemy to disbelieve since it touched them? Or does illusory creature even allow firing an arrow since that would not be a part of the creature, but a weapon?
Illusory object states that it creates an stationary object. Once you create it, you cannot move it. It is like an animated hologram.
As for the pieces, as long as it does not create 2 separate masses, I think it is OK.
If an enemy tells them the object is fake, they still need to interact/seek and pass the save. Knowing it is fake is not enough to disbelieve it. Every creature has to pass the save individually. Even your allies.
As for Illusory Creature, its strike can be whatever you want it to be. An illusory creature can be whatever you want it to be. You can move it from wherever to wherever inside the range (creatures can teleport afterall). That said, doing something weird or unrealistic might cause other creature to suspect it is fake and get a free save. That is 100% dependant on the GM.
The creature disbelieves when it strikes or otherwise actively touches the illusion, like a grab (touching and being touched are 2 different things), when it seeks and passes the spell DC or when it just passes the DC because you did something really unrealistic with it (like the example of a dragon hitting like a wet noodle might cause an immediate check. As it happens during your turn, it has to be either a free action or a reaction). If any of those happens, the creature takes half the compiled damage and "heals" the other half.
For illusory object, I would allow moving objects - like the waterfall example, or a windmill, or a pendulum that swings back and forth - things like that. But it has to be repetitive. It doesn't move intelligently in response to either observers, or caster's further wishes. It is set and forget.
Similarly for a weapon - if an enemy failed to disbelieve the illusion, they might mime picking up the weapon and swinging it. But the illusion of the weapon wouldn't move. No one else would see them holding it, and if they pay any attention to what they are doing at all, they would continue getting saving throws against the effect pretty frequently. Also if they move out of the area, then they would no longer even have the possibility of believing that they were still holding the weapon.
Yes, each observer has to disbelieve the illusion independently. Calling out that it is fake would be considered an Aid action.
I'm not sure about Illusory Creature making ranged strikes. The rules don't prevent it, but they also don't give any indication of things like range increment. I would probably allow a ranged attack and rule that if the accuracy is too high for the normal range of the apparent weapon, that would qualify for a disbelief check.
Same with the movement speed. If you move the illusion too fast, observers will get a disbelief check for free.
I don't think that its attacks would cause a disbelief check. If that was the intent, the spell rules would have stated that more clearly.
Illusory object acts like a hologram film but be careful because it's need to be an "illusory visual image of a stationary object", so no moving around the area and can't do longer or too complex movimento to prevent it to be so good as an Illusory Scene.
This will depend from your own and GM notion of what's the illusory object limits. But in general it cannot move from it's original location or be moved and cannot be touched (it isn't a quasy-real illusion) but if failure in disbelieve test creatures can still believe that touched something (GMs needs to ajust the things here, a creature that's don't know that's is an illusion can interact with a illusionary wall may think that it's sense the touch, while a creature that knows that's the wall is an illusion still know that's a illusion can trespass it but still can't see through it while it's not disbelieved. I also recommend to do circumstance bonus/penalties in disbelieve test to prevent a creature that's already knows the illusion to have too much difficult to disbelieve it and creature that's have reasons the believe that's is true to easily disbelieve it). This isn't in spell description but as GM I won't allow animations with duration that's more than 6s (a normal round duration) to prevent it to be better than illusory scene. So you can make a ballerina spinning in place and in loop but the movement need to be repetitive.
In general, in battle the best uses of illusory objects it's to create walls, bars, small labyrinth, fake hazards or fake "safes" (like a fake bridge over a cliff) than creature that can't go to anywhere.