Solution : https://service.sap.com/sap/support/notes/376976 (SAP Service marketplace login required)
Key words : 
symptom euro conversion additional key words euro, infocube   customer   customer group  sales revenue  customer 1, customer   customer group  sales revenue  customer 1, customer group  sales revenue, ods table      infocube fact table2, convert specific key figures, conditionskey performance indicator attributes, conversion takes place field-, ods object      infocube, 'normal' infocube approx
Related Notes : 
       
| 1273778 | Currency conversion from SSK into Euro in SAP BW | 
| 1090503 | Venezuelan currency conversion - Conversion in SAP BW | 
| 811461 | Euro conversion no longer available | 
| 448697 | Euro conversion: RSDD 822 | 
| 446683 | Euro conversion: poor performance for cube conversion | 
| 446028 | Euro conversion: SQL error -270 | 
| 443760 | Euro conversion: No restart after termination | 
| 414941 | Euro conversion: PSA tables are not converted | 
| 414630 | Euro conversion: Conversion of ODS tables provides incorrect | 
| 406907 | Euro conversion: Error for converting IEP | 
| 396186 | Euro conversion: Conversion of stocks | 
| 393325 | Euro-Conversion: ORA 1722 or ORA 1401 | 
| 390359 | Euro conversion for SEM | 
| 385688 | Euro conversion: ORA-0264 for PSA conversion | 
| 379026 | Euro conversion: poor performance w/ PSA conversion | 
| 376866 | Euro conversion: Rounding error during conversion | 
| 376284 | Euro conversion: error during conversion | 
| 369170 | Euro conversion: Poor performance during cube conversion | 
| 327741 | Euro conversion for BW |