I’m not sure I understand your question about masks. Objects can have 1 mask for all animations or seperater masks for each animation or for each frame. The mask setting and the current animation decide which mask is used.
If you had an animation of someone swinging a bat you could align a mask on each frame to follow the bat. So, it would collide in the right spot. Most of the time that type of accuracy isn’t needed and the same rectangle or loose shape is enough. You usually want the mask to loosely fit the image. When the image is small, nobody will notice the difference between a perfecting fitting mask but the more complex a mask the more it takes to process each one on each frame of the game.
There are times when you need 2 masks or 2 objects. So, you can use a 2nd hidden object with the same or a different mask but this should be used only when absolutely necessary because again resources.
As for the point is inside. Sometimes inverting a condition doesn’t work as expected and you need to put the non inverted condition inside a Not condition.
This can be confusing.
This might help.