Here is CMAP vector charts zoomed out as far as possible (showing the entire world). That archipelago is even shown on this scale (I put a small red X on it), and is shown on all zoom levels down to detailed scale.

Besides, how accurately did they expect those reefs to be charted (maybe they are very accurate, I don't know)?

My bet is that they were looking for an edge and planned to cut them close on purpose - and made a mistake.

Electronic charts have nothing to do with it. We chart electronically exclusively, but every route made is "flown" at the closest zoom level to make sure nothing was missed. Our chartplotter even does this for us (zooms and "flies" a route - we have to provide the eyes). After that, and while underway, we regularly look at the next 20nm or so at high zoom just to check.

Do these boats have radar? That would have been useful there at night.

Mark