Vocal reconstructions are even trickier as vocal chords degrade real badly over time. Nobody knows what Cleopatra actually sounded like in life, unless if somebody did describe her voice she would’ve the average female voice. A linguist could guess Jane Austen’s accent, to the average reader her voice’s just something they project their ideas onto her.
Due to the rise of sound recordings, it’s become incredibly important to distinguish people’s voices which is important to voiceover artists wishing to impersonate those and linguistics alike. It’s also incredibly important to musicians and listeners as it preserves such voices that would’ve been lost to time.
As for Jane Austen and her ilk, what they actually sounded like is left best to linguists and those curious about it.