yea rpgmaker programs are very easy to use if u know what to do. the difficult part is enable/modify scripts, if they exist of course, and those are created with java/html5 language. (old ruby scripts doesen't work anymore i think, i haven't tried yet)
idk what method this dev have used to animate the sprites or control the images, but if u can figure it out u can add whatever u whant as long u have the sprite/image to do it, the time to make it, and the imagination to create more scenes ( ͡° ͜ʖ ͡°)
btw, the game will have a final update (with the final ending). if i was you i will be VEEEEERY cautious on the stuff i whant to change/add, because it will surely break with the next update.