I’ve been making assumptions about your knowlege and skill level, and Neil is right - assume nothing and make sure your machine is true. I think you need to ‘start from scratch’ persay. I have had to do this several times on both machines. Go through every bit of the setup process of your machine documentation again, and ensure that your calibrations are all correct and true. I also run a level (at least half the width of your gantry) and use a digital level on top of that.
This can be hard to figure out, but if you have a 4x4 gantry machine, sacrifice a piece of wood (or use your wasteboard - not recommended) to make a square 47"x47" at a minimal depth, and cut a square. Is it visually square? Measure from each edge to confirm. If it isn’t, you need to do it again. These machines do kinda suck for that, because I did it, but it still isn’t right. Re-evaluate, and do it again. If your calibrations are out, this will show you.
Take a pause right here. These are two different machines - a computer, and a cnc. The computer is a stupid device that does what you say to send a file to another stupid device in the cnc. It is very important to establish a clear communication between the two, and make sure that each one is doing what it is supposed to do.
I’m going to leave ‘tiling’ out of this for now, because that is another whole level of complication that I don’t think you are ready for yet. No offense intended, but don’t add complication until you have the basics.
You appear to have some settings wrong in one or more of your design software, or your cutting software. It may be in your machine settings in Easel, or it may be in the size of your project before it is imported into Easel. I’m still making assumptions - I can’t see what you are doing, I can only read about your frustrations and try to figure out what is happening, and try to assist.