Searching for nested attributes is not supported by default in SAP Commerce (Hybris) when using the Backoffice advanced search. If you are required to implement such a feature, the two options would be:

1) Extend the advanced search logic (see AdvancedSearchController class)

• Not recommended due to its complexity.
• Your particular change is item-type specific rather than a general improvement, making the effort less worthwhile.

2) Add a productCode attribute to CustomerReview and use a PrepareInterceptor.

• This is the simpler and more practical solution for your use case.
• The interceptor ensures that when the product changes in a CustomerReview, the productCode is updated accordingly.
• You can then use the productCode attribute in the advanced search widget.