The only trouble with translating is that the lyrics to this song largely resembles a seven character poem in some parts and has various play on idioms. I did not grow up knowing many of these, and so asked my friend whom actually knows a bit about these idioms.
Will try my best to explain because otherwise it makes little sense.
Please correct me if my explaination is inaccurate or a little off, i'd love to hear your thoughts. :D
I think its a song worth discussing because it says a lot beneath the surface even though its such a short song.
(full version under 3 min)

........
A Thousand Years - Sun Nan
As far as my eyes can see
there lies only endless castles and fiefdoms***
Why take heart in what history will tell?****
An unflawed thing of perfection,
A song of unimaginable grandosity
Yet none will hear or ever know of it [as I did]*****
You too, have already become so distant
the brilliance of times gone by
the heartbeat heard from a thousand miles away*******
--------------------------
First of all, the title itself warrants some explaination. The literal translation of Qian qiu meant a thousand autums, and is a word that is commonly used to describe the long and prosperous reigns of emperors/empresses. Its not a counter for anything but an expression.
*the speaker is moved by seeing the thousand lights. (most likely a ruler looking back at his kingdom, the accomplishment of his life)
**drinking to say farewell to this life (and basically to look back on the former glory and regrets of the life lived)
***I interpret it as sort of a both accomplished and a sense of loss. All my life i've conqured so many castles and all the land the eye can see obeys me. But also means that thats the only concrete legacy left to prove his life. This sense of regret is somewhat common sentiment: sacrificing loved ones or human relations to war and coquest.
****comes from a couple of idioms, especially placing "slander" and "praise" side by side means that there will be an eternal argument wether so and so's rule was just or not. The ruler will always be jueged by the people for generations to come.
Here it could refer to the various interpretations people have of Empress wu's rule.
Overall means that there are far too many ways to argue wrong and right, why be bothered by the comments of others if you've live a life in which you can face with no shame? And besides you cannot exist to please everyone. One's own heart is the judge of ones deeds.
*****all things that describe the ruler's reign, how he saw it, now that he looks back on everything, admist all the mistakes, the good and bad
******the word used here is Jing Hong ”惊鸿“ is kind of hard to describe because its not really anything concrete nor anything grand itsel, but a kind of feeling you have when you look at something grand, for the first time, unexpectedly. My friend said its like you were standing behind someone looking into the misty mountains, both of you look into the mounatins (You don't know this person). All of a sudden an eagle flies overhead calling loudly. The person in front of you by chance suddenly turns to look at the eagle, and in the instant the he/she turns, you are absolutely astounded by how beautiful this individual is such that it is a thing you've never encountered. And all the while in the backround is below you, tall mounatins in the distance and mist encricling everything.
Yeah. Basically a feeling that also connects with the enromity of nature itself.
I really have difficulty directly translting this line and kind of paraphrased it.
The half after the lyrics are a revisitation of a reckless youth, because during that time one only thought to run forward and never look back. ******* the heartbeat from a thousand miles away is also from a play on an idiom, which I interpret as the feverently love and emotion that could not be put out. The time when anything could be done for the sake of love diregarding power and all else.
But they were quickly discarded with time, and only so short lived once reality was not only seen but felt.
Yet there isn't really isn't anything to say, as the song ends there; partly because its th unchangeable past, and partly because he undestands finally that no one could be faultless, more power comes with only heavier responsibility and faults.
