We are investigating the issue and will update you soon.
There is some limitation when using Aspose.Words via COM. In this case Replace method expects a System.Text.RegularExpressions.Regex object but you are passing RegExp from Microsoft VBScript Regular Expressions 5.5 so such exceptions are expected.
Can you please share your complete code including ReplaceHandler class? Our product team will further analyze the issue if it can be fixed once you share the complete code.