Function authoring_table_cell 

pub fn authoring_table_cell(
    shape: &ResolvedShape,
    table: &ResolvedTable,
    row_index: usize,
    column_index: usize,
) -> Result<(ResolvedShape, ResolvedTextBody), RenderInputError>

Projects the exact merged cell box used by table lowering for authoring. Continuation cells have no independently sized text owner.