Rhona - to avoid any confusion, the five 'changed' entries and the 6 'thematic' entries are two distinct groups. All six of the 'thematics' are 'chimaeras', and
all six are answers to their relevant clues, allowing for the 'chimaera' convention in each case.
There are 5 'changed' ones where only four are needed, and 6 thematic 'chimaeras' where only 4 are needed, because Aedites has simply gone along with usual practice where checked crossings occur - it's difficult to see what else he/she could have done, without a probably impossible redesign of the grid.
Hope this answers your query.