The absence of documentation can be considered a form of tech debt, and tech debt can be deadly. In addition to what you're endeavoring, you could ask yourself,

The absence of documentation can be considered a form of tech debt, and tech debt can be deadly. In addition to what you're endeavoring, you could ask yourself, what risks am I actually mitigating by back-filling missing or poorly written documentation? The answer should guide your decision making. Sometimes, it's just a case of too little, too late.