This problem will solve by time. The longer you play this game the more you will see differences in those icons by taking a look at heigth and which the side the symbol is located on if you turn your had by a few degrees, still on a gun.
I'm not sure how much time you think is needed to learn.. I'm a relative newbie compared to some on this board, but I've won 30 out of the last 40 or so matches, so I'm pretty sure I've got a pretty good grasp of the game so far (although having a damn fine crew probably has something to do with it as well xP).. but I still think this could be a useful thing to have.
On the Mobula for example, it's been my experience that while manning one of the wing guns, the engine behind you might be distinct from the others, but the opposite wing engine and the main engine tend to hover closely together, and it takes turning all the way around to differentiate the two. On the Spire as well it can be hard to tell if the main or turning engines are damaged if you're on the top deck, as the one behind you and the ones below you both move to the bottom of the screen in a relatively small space (and since the guns are off to the side, the icons aren't necessarily spaced apart well enough to tell apart).
I'm not saying this is the experience on all ships, but on certain ships it would be nice to be able to tell the icons apart more easily.
Well, as an engineer has to move to the component that should be repaired anyway and to do so turn around to face the component he can easily determine where it is.
This isn't exactly correct, as on the Mobula the hull is split into two and therefore requires at least two Engineers that cover their own areas as well as manning the guns when not repairing - it's in a situation like that that I see being able to filter out unnecessary information would be useful. As I said before, it's annoying to have to jump off a gun to go repair an engine, only to realize it's on the opposite hull and the other Engineer hasn't realized it's his problem to deal with.
As a pilot you usually notice which engine is broken by the symbols (since you're often centered) and the behavior of the ship.
I suppose.. can't say I've had the pleasure of flying with a pilot who knew their right from their left, but that's just my misfortune.. >.<
To sum it up: I guess you will dominate this problem the more you play, it is something you will gain a feeling for quite quickly.
If someone sees it another way, I'll be glad to hear it though! Maybe it's just me seeing it that way.
You make good points, and the more I think about it the more I realize that this suggestion is specifically aimed at an issue I have with Mobula's (and Spire's to some degree).. on other ships I suppose it makes less sense.
However I have seen suggestions on this board for a sort of 'quick command' menu for captains to issue orders, and I could see marking the engines with symbols making non-verbal communication somewhat easier.
As the game stands now though it may not be as useful as I thought..
By the way, this is what I envisioned it looking like: