Cheers.
I might be misunderstanding your query but I think there's two different bits here:
1: Hard versus soft cover.
I don't make a distinction because at the scale we're playing it, I don't feel it's likely to.
Yes, if I am hiding behind a hedgerow, I could be hit by stray fire but the odds would be quite small and my opposition is armed with bolt action rifles (mostly likely), meaning they aren't putting out a high rate of fire.
If I am looking at a hedgerow and I know there's a German somewhere behind that 10 yards worth of hedge, firing indiscriminately in there is not likely to do much good if I am on my own.
That's more of a squad level tactic in my opinion.
Now, you could easily change that, if you feel otherwise.
"Figures hiding behind soft cover, and known to the firer may be fired upon, Shock dice only"
This would cover that if I see you across the hedge and you pop down, I can still bother you by firing near your position.
If the guy moves behind the hedge, he's no longer known to the shooter so he can't target him.
For the second question:
"By the rules, it makes no difference to stand in the open with some light cover at certain distance or directly behind it. And i think it should be some kind of distinction."
If the cover is in the distance and the figure isn't in contact they cannot hide, hence they will always be a target, but any fire they take is Shock only.
If they are right behind the cover, they can hide and be out of fire completely.
This is probably easiest explained by setting it up on the table and doing the "models eye view" thing. Anything more than an inch or so behind a typical model wall is just going to indistinct little blobs.
The shooter is going to register movement and can take it under fire, but their chance of causing hits on a few crouched figures on the far side of the obstacle is small enough that we disallow it in the rules.
Now, if the guy is right by that wall and sticks his head up to fire, he's silhouetted pretty well and I have a decent chance of popping him.
Make sense?
I am not sure if we're talking past each other a bit :-)