I am trying to produce a report which should ultimately be exported in Excel format.
The template of the report is available to me in Excel.
Is there a smart way to "reverse engineer the Excel" in order to design the report (if possible respecting the position of the cells).
I thought about importing an html version of the report but I was wondering whether there is already a standard method for doing that before starting to reinvent the wheel.
I believe you are trying to achieve reporting bursting feature in an excel format.
You can try using Pentaho Reporting Output. Pass your pentaho report name to this step and choose the output as Excel. Note: you need to have a pentaho report built using Pentaho report designer.
Alternatively, you can use the Excel Output step in Pentaho DI. Link your excel template in the "Excel Template"/"Use Template" section of the step. Pass you reporting query and generate the excel report.
Hope this helps :)