Generally speaking maybe, but there are many cases in which the above doesn't apply.
Indeed, I know a woman who was raised in Macedonia, having both Albanian and Turkish parents. She was schooled in all three from a young age, as well as learning them in the home.
Likewise, I have Polish friends who are teaching their children, from the cradle, Polish and English. One friend has a 5 year old daughter who speaks better English than some Brit kids I know.
But if I'm Polish and translating a Polish poem into English, then I should be mainly concerned with the Polish side of things - let's say I use an unusual style or rhythm, break with the English poetic tradition if need be, and maybe introduce a little "Polish soul" into the finished English text. Is that wrong?
I'd say it depends how much it is necessary to convey the meaning. I had a macedonia colleague who translated Seumas Heaney (Irish poet) into Macedonian. Anyone familiar with heaney's work will know it is often multi-layered and full of colloquialisms (or even invented "colloquialisms" and phrases). I asked how he managed to convey all these meanings when the macedonian words often lacked the (same) mutliple meanings as the English words.
He said, "You sometimes just have to choose one of the meanings and go with that one," Likewise, he was translating a poem about a woman ironing. I realised the rythym of the poem was the same as the rythym of ironing... how to do that when a language has a fixed stress pattern? Maybe you can't.