【C#】Utils配下のメソッド戻り値が正しくない about kanaria HOT 1 CLOSED

/// <summary>
/// 半角ASCII文字かどうかを判定します。
/// </summary>
/// <param name="target">判定対象</param>
/// <returns>該当:true / 非該当:false</returns>
[DllImport("kanaria_core.dll", EntryPoint = "is_narrow_ascii_for_utf16",
    CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Unicode)]
[return:MarshalAs(UnmanagedType.I1)]
public static extern bool IsNarrowAscii(char target);