Is the term "fire and forget" well understood?

It's common military terminology, so I would think that anyone who has a passing familiarity with military culture and military idioms (geeks tend to fall in this group) would understand it perfectly well. Military fiction is a common form of entertainment, so this phrase exists in the nebulous realm of pop culture as well.

I wouldn't call it universal, and I wouldn't call this usage common, but I think most English-speaking Americans would understand you.

You're absolutely right.

The expression was first coined in the military sphere in the 80s when the so-called "intelligent munitions" were talked up by the industries to the western military bodies. Examples of these munitions were the MLRS, laser guided bombs or cruise missiles.

The main selling point was the impunity of the operator.

The expression then reached the IT world where reliability comes as a major quality.

The phrase spread from the military to the IT industry quite naturally because of the important involvement of the latter in the former.

The meaning of the term seems obvious to me now that I know the etymology, but I doubt most average folks know what a fire and forget weapon is either. Put it this way... I just found this page by googling the term after someone described a coworker as being "fire and forget." In the context the term was used, I could tell the meaning was positive, but without that context I would have assumed it was negative... like the person fired a weapon (did some work) and then forgot to check whether or not it hit the target (never checked to see if the overarching goal of the work was achieved).