The XLSX export will be aligned with what is already done in "Cross tracker XLSX export": each level of sub artifact link will lead to a duplication of lines.
Given the following structure

This will lead to this kind of table (without the colors)

The example .xslx is here.
Business rules
A block of field is the list of fields defined in the SELECT
part of the TQL query
Each expanded level of artifacts will lead to one block of fields
Given an artifact at level N that have M links at level N-1, there will be M duplication of N block.