When I checked the installation log shared by Ertan, I do see that the locale passed to initcluster script is the same as returned by the getlocales executable.
That is log file line no 5544 and is cscript logging. There is no problem here.
If you check log file line no 5606 you will see that the encoding is not correct just before initdb
Maybe this is related to BAT file usage? I don't know.
Ah, I see it now. Let me take a closer look
That line gets printed from within the initdb and is not printed by the script. @Thomas Munro I may be wrong but I guess fixing the code might fix this. Can you please share your patch so that I apply it on top of the last released source version, generate the installer and confirm the behaviour?