Hi Benjamin,
I found the profile files under SUM directory
G:\usr\sap\QAS\SUM\abap\system\QAS\SYS\profile\DEFAULT.PFL
G:\usr\sap\QAS\SUM\abap\system\QAS\SYS\profile\QAS_DVEBMGS02_EXSAPDQAS
Checked both, the instance profile has
zcsa/system_language = E