You should be able to copy and paste textures from other blocks, you should also be able to add animations!!!
to add an animation, there should be a button in the corner whilst editing a blocks texture that says "add animation," and once you click it, a button will appear that says "add frame." once you click it, it will move to the next frame of the animation (the block model will be the same) and you can edit the block texture each frame that you want to change, and as well as the "add frame" button, there should also be a button that let's you choose how many in game ticks you want it to take to move onto the next frame. To copy and paste there should be 2 buttons, one says "copy," and the other says "paste," once you click copy, there should be blue box that appears and you can move it about and make it bigger to choose the part of the block you want to copy, then the "copy," button should be replaced with a "done," button, and it saves so when you press "paste," there will be a bunch of textures that you copied and you can select one, maybe make it smaller, (if the current pixels are smaller than its pixels) and drag it around to where you want to paste it. Utk.io, I hope you take this into perspective and make it a reality (Plz)