YES!! IT WORKED! 
It seems that the UTF-16 is really not supported. So I changed the encoding of D:\OrangeOnGo\Source\OrangeOnGo\OrangeOnGo.h and D:\OrangeOnGo\Intermediate\Build\Android\OrangeOnGo\Shipping\OrangeOnGo\OrangeOnGo.h to UTF-8 (with BOM). It looked like it’s fixed. But because these headers files include other .cpp and .h files, I need to change them to UTF-8 as well (as you wrote). Firstly it showed error with some .h files (because of the UTF-16) and when I change their encoding, it showed error with .cpp files which were included (that means I need to change them too). After I changed about 6 .cpp and .h files it finally worked. The build in Visual Studio was successful and packaging in Unreal as well. Thank you guys… I finally heard the successful beep sound from the Unreal Packaging after a few weeks!
(SORRY FOR THE ATTACHED IMAGES… I WAS WRITING FRISTLY SOMETHING DIFFERENT)