My oldest son in law, who may be the world’s worst pistol shot, brought over his new S&W 9mm. On a man sized splatter target at 15 yards, he shot into the ground or the very bottom edge of the target. Then I shot the pistol and found that it was very accurate. He shot it again, and hit the ground every time, which is about 3 feet low at 15 yards. I had him shoot the pistol off the sandbag rest and he found the center of the target. Since then, in subsequent shooting sessions and a little suggesting from me, he has gotten much better.
When I have to adjust sights on a handgun, if the sights need adjusting, I use the sandbags. I’m a pretty fair shot, but using the bags takes me somewhat out of the process. When I have the sights set right, and know for sure the pistol sights aren’t misaligned, then I’m confident that any good or bad shooting from now on is all on me.
My 380 EZ sights were off from the factory. It shot a bit wide right. I put it on the bags and confirmed it was the sights, and not me. I did the adjustment, used the bags again till I had it just right. There is no shame in utilizing a sandbag rest to verify sight adjustment. We do it with rifles.
As for the OP’s 9mm EZ, from what I’ve read it appears to be a pistol sight problem and not user error. That seems odd, but so be it. If the 9mm EZ sights are as simple as the 380 EZ sights, it is hard to imagine them being messed up to any degree. But I guess they are. So...order some tritium night sights and have them put on. That’ll be justifiable to the wife.