I wonder why "Aberdaron is in the north of Wales" is marked wrong?
The far more common expression in English is 'in north Wales' rather than 'in the north of Wales. However, even though it sounds awkward, it is not actually wrong. It is now an accepted answer - it may take a little time for the change to go through.
"gogledd Cymru" looks like "the north of Wales" to me - two nouns forming a genitive phrase. Or is "gogledd" an adjective that precedes the noun?
Correct - two nouns in a genitive relationship. gogledd Cymru, de Cymru, canolbarth Cymru, etc are usually rendered in English as 'north Wales, south Wales, mid-Wales, etc'
My first thought about this sentence was "Aberdaron is in north Wales". But according to the syntax that DL used so far, this would be Mae Aberdaron yng ngogledd Cymru.
Since Yng ngogledd Cymru stands in the first part of the sentence, I tried "In north Wales there is Aberdaron", but it was marked as wrong.
So why is Yng ngogledd Cymru standing before mae Aberdaron?
Is there any difference in meaning or emphasis between Yng ngogledd Cymru mae Aberdaron and Mae Aberdaron yng ngogledd Cymru?
Yes, as you guessed, Mae Aberdaron yng ngogledd Cymru is the normal, neutral order with no particular emphasis. Yng ngogledd Cymru mae Aberdaron emphasises the yng ngogledd Cymru bit i.e. the fact that it's in north Wales. You might say this kind of sentence to contradict someone who, for example, says Aberdaron is somewhere else or in answer to the question Ble mae Aberdaron? "Where is Aberdaron".
You can usually put any part of the sentence to the front in Welsh in order to emphasise it. It's a really common thing to do. We do it in Welsh English to, "In north Wales Aberdaron is"!
@ ibisc So are you saying that " In the North of Wales is Aberdaron" isn't actually wrong then? It was marked wrong for me, but it looks like a perfectly good translation to me.
I agree with you. It's all about context and emphasis: e. g. "In the North of Wales is Aberdaron, home to a rare race of mutated crimson dragons."