Translation:You have letters from ten girls here.
I think the here at the end is OK, but what you've written is also OK. Here can be first, third, fourth or last - last place is the least clear in my opinion - spoken it's OK, but written the way they did you could think that "ten girls here" wrote letters. I wrote "You have here letters from ten girls" I am a native speaker and the answer I was told was "You have got letters from ten girls here" - I thought "got" was missing. "You have got" sounds British to me.
It is true that a native speaker would not say "You have here letters." On the other hand, there is nothing odd about "You have here letters from ten girls."
The difference is that if the sentence is going to modify "letters" with a (long) adjectival phrase, then it is sound style to insert the brief word "here" sooner rather than later.
Yours is better stylistically and definitely the most natural sounding. I admit my version sounds wrong the more I repeat it. I think spoken with the right intonation you could get away with it, but just like putting 'here' at the end of the sentence, it also sounds a bit weird where I put it...