Solution : https://service.sap.com/sap/support/notes/991549 (SAP Service marketplace login required)
Key words : 
sap note 766516 authorization object/role, face severe problems withe, <sapsid>adm user required, official bia service connection, sap system user, <sapsid>adm user, terms bi accelerator, investigating bia problems, trex python-admintool, tunnel xserver request
Related Notes : 
       
| 1060387 | Analysis with incorrect results in BIA queries | 
| 999840 | BIA 7.00: Revision 31 | 
| 995756 | BIA 7.00: Revision 30 | 
| 992064 | BIA 7.00 + BIA 7.20: BIA system check | 
| 883726 | BIA 7.00: Central Note SAP NetWeaver BI accelerator | 
| 766516 | Authorization object/role for TREX |