Unless lava did not actually enter the library, wouldn't anything written on parchment been burnt to cinders? I guess if there are stone tables, there might be a potential find, but outside of that, I can't imagine anything written to have survived a lava flow.
Scientists have discovered new ways to read 1,800 charred manuscript scrolls already found in the ruins of the so-called Villa of Papyri at Herculaneum ...
The Herculaneum Society meeting gasped like spectators at a firework display when Nigel Wilson, of Lincoln College, Oxford, showed a slide of a blackened roll of papyrus on which no writing could be seen, and then showed what it looked like after multi-spectral digital imaging had been used on it. Clear lines of ancient Greek script appeared, like invisible ink held before the fire.
Imagine harder.
Many of the charred manuscripts were discovered in the early 20th century and dumped in the sea when assumed to be lumps of coal. Currently these same type of black lumps are being scanned, read and transcribed.