While reviewing the specs for the "caption" role, I've realised that the characteristics table, in particular the "Required Accessibility Parent Roles" row, is not fully reflecting the requirements listed above.

In particular

The caption is a descendant of a group, figure, grid, radiogroup, table, or treegrid.

while in "Required Accessibility Parent Roles" row, only

figure, grid, table, treegrid
are listed

https://w3c.github.io/aria/#caption