Is there a way to intercept and correct keyboard input?

Some of the letters on my laptop (MacOS) don't register input sometimes, some of them often double-type the letter. So far I couldn't find any software to fix that, by that I mean some AI cleverness to intercept my input and correct it a bit. How can I learn to write something like that myself, it seems like an easy program to write, I just don't know how to start and what languages are suited for this. Help please. By the way, it's way easier to buy a new keyboard, I'm just interested in the implementation.