No bednobs, wrong.
A caution is a note attached to the title register that requires that the land registry informs the holder of the caution if an application is made to sell it.
Nothing more, nothing less.
As you correctly observed it is not a charge so does not entitle her to a split of any proceeds - not without further entitlement as determined by other legal action.
It might be as well to resolve why she done this, as it sure is going to delay any sale when thtime finally comes.