Yes, there are still music scores of ancient Tang poetry and Song lyrics, and there are quite a lot of them.
However, those musical notations are different from today’s simplified notation and five-line notation. Those ancient musical notations are all “literary notations”, which use words to express actions such as hooking, vibrato, and rebound, such as Gao E’s continuation. It is also mentioned in the last forty chapters of "Dream of Red Mansions".
The reading method of "literal music score" has long been lost, so even if people today get these music scores, they cannot restore the classical singing method of Tang poetry and Song lyrics. The music scores of the ancient poems and lyrics we see now are all sung today. What modern and contemporary people have compiled is no longer the original version.
As for the ancient music that has been passed down to this day, it is all passed down from generation to generation by musicians and masters and apprentices. Only a small part of the ancient music has been passed down to this day.