Yes, we can extract coordinates from plots automatically. @chartgerink and @TheContentMine developed this for funnel plots. See https://arxiv.org/abs/1709.02261 . Development continueshttps://twitter.com/KirkegaardEmil/status/957529994850336768 …
Unfortunately, as you say, vector figures are uncommon and not at all present in older papers, so good (even if appropriate) methods must be found for raster figures.