I think tracers are currently less visible than they were in reality. This is probably due to limitations in the range of light intensity displayable by a computer monitor. They might match up to gun-cam footage, but such footage is subject to the same intensity limitations and should therefore not be used as the basis for in-game tracer visibility.
Here's how I see it.
Reality:
Tracers bright from nose mounted guns.
Tracers brighter from wing-mounted guns.
Tracers brightest from the perpective of the target.
Game:
Tracers visible from the target.
Tracers dimmer from wing-mounted guns.
Tracers nearly invisible from nose-mounted guns.
To make up for the fact that in-game tracers are not and can never be incandescent like their RL counterparts, I would suggest two things:
1) Make tracers a different color, which is not used anywhere else in-game. Hot-pink would be a good choice.

2) Make the tracers a bit bigger (especially in "diameter")