After extensive testing I reached the conclusion that one of the tools packed with my patcher ('sed') is flawed, at least its Windows builds are. I tested multiple precompiled variants of the tool and they all had trouble handling operations under a Chinese Windows-environment, which also begs the question if it does not have issues under other OS languages.
I was faced with 2 options, writing my own binary patcher or finding a suitable replacement. Luckily I found another candidate: 'gsar' tool, which not only does the job very well under the environments where 'sed' failed, it is also very lightweight, fast, and needs minimal dependencies; the script itself is even bigger than the 'gsar' tool. Ironically this tool was ported to Windows back in 2008 yet it works perfectly today even under Windows 10 (x64). I had to rewrite most of the script to use the new tool, but it seems that it was worth it; the patcher has now dropped from 1MB to under 100KB since I discarded 'sed', 'grep', and all of their dependencies (DLLs). I cannot be sure that now everything is bug free, but I have done a fair amount of testing under Windows 10 (including native traditional Chinese build). If you find a bug, let me know.
Make sure to get the last version from the usual place:
https://www.shenmuedojo.com/forum/index.php?posts/10013/