Build error output is broken

After build failed, some character is showing just ???.
So I make a simple error and compare output with 4.19

Build result
4.19

error C2065: ‘asdfasdf’: undeclared identifier

error C2143: syntax error: missing ‘;’ before ‘}’
4.20
error C2065: ‘asdfasdf’: ??? ??? ???.

error C2143: ??? ???: ‘;’??(??) ‘}’ ??? ???.

Log at UE_4.20\Engine\Programs\UnrealBuildTool\Log.txt also showing broken character.

ParallelExecutor.ExecuteActions: D:\Develop\Unreal\DDakji\Source\DDakji\DDakjiPlayerController.cpp(116): error C2065: ‘asdfasdf’: ������� ���� �ĺ����Դϴ�.

ParallelExecutor.ExecuteActions: D:\Develop\Unreal\DDakji\Source\DDakji\DDakjiPlayerController.cpp(137): error C2143: ���� ����: ';'��(��) ‘}’ �տ� �����ϴ�.

This log text saved as UTF-8 I think. (when trying Save As, encoding shows UTF-8)

Ive changed windows and visual studios language but had no effect. I think its a sort of ubt`s problem. Maybe language/encoding error.

How can I fix it? I want to change ubt`s output language if possible.

Well, there is some mistake or I saw something wrong. I changed VS language to English and output was out as English. Still have problem but I can go further.

I won’t call this a solution (it isn’t) but an observation. The diamonds (AKA WTF diamonds in some circles) indicate that the log is being presented as a non UTF-8 encoding. Switching to English ‘solves’ the problem because English is functionally ASCII only. At a guess I’d say that there was a bug in 4.20. If you were describing an HTML page, I’d say either the browser or the HTML page had the wrong default encoding.

Hopefully this problem will get resolved in the next engine iteration.