Defending "bad" grades and what could I aim for [Abitur]

First of all a little background:
I want to study engineering, I'm currently at the German School in Oslo, I've moved to Norway a year ago and the Abitur (German A-Levels) is quite a mess.

Abitur grades go from 0 to 15, 14/15 being considered equivalent to A* by most Universities it seems.
13~A; 12/10~B and C etc. going down.

Then there's an Overall grade that gets calculated based on the final exams and grades from various semesters according to quite a few tedious rules:
AAA=1.3
AAB=1.5
ABB=1.7 (varies from uni to uni, I've seen this value up to 2.0 I think)


I have 14 points in all sciences, being physics, mathematics and biology (and in arts for some reason), which is great because A*A*A*!
Except not, I can only take up to two of them to the final exam.

And I'll also have to take German, Norwegian and Politics in Norwegian to the exam. The nice thing is: these are my 3 worst subjects.
And being exam subjects they count a lot more towards calculating the overall Abitur grade.
I believe I might be able to manage a 1.5-1.7 overall, but I'm not completely sure.

Now to the actual question:
Do you think it would make sense to try and defend my "bad" grades (well I still have 11 and 12) in Norwegian and Politics by saying that they are a challenge to me as they are taught and examined in a language I don't speak too well? Or would that only be perceived as an excuse, or worse even as a sign that I'm stupid as I'm not able to learn the language?

German is indefensible anyway as "major couchpotato" is not a good argument.

And also, what do you think I could realistically aim for? I am pretty sure I will get quite a good reference and I guess I'll be able to keep up the high science grades, but the rest weights me down quite sensibly (my average for last semester was ~1.6, or 12+ points).