Unfortunately, most studies focus on the blocking of liver damage by quercetin, which has been shown many times to be possible.[2][3][4] But I managed to find one study that shows the reversal of liver cirrhosis in rats.[1] Since most people are likely to develop liver damage without knowledge of nutrition or prevention mechanisms, reversal of liver damage seems like a more interesting topic.
[1] https://pubmed.ncbi.nlm.nih.gov/28802065/
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5819566/
[3] https://www.spandidos-publications.com/10.3892/etm.2017.5329
[4] https://onlinelibrary.wiley.com/doi/abs/10.1002/ptr.7104