Hi LTT,
This is a Windows issue, and not the EmEditor issue. Windows escape and unescape command lines because a double quote (“) and a backslash () has a special meaning. For instance, “ means “ so you will need to use “ to send a backslash and a quote. It is a very complicate matter, so please refer to Microsoft documents in order to understand how to escape command lines. While the command options are documented in the EmEditor Help, this Find in Files command option is not recommended to use directly. It is internally used by EmEditor.