We have evaluated your presented scenario while using the latest version of Aspose.Cells for .NET 8.3.2, and we are able to observe the inconsistency as mentioned in your post. The version information extracted directly from the Workbook.BuiltInDocumentProperties.Version property is different from the one available in the Workbook.BuiltInDocumentProperties collection. We have logged an investigative ticket CELLSNET-43355 in our bug tracking system to look further into this matter. Please spare us little time to properly analyze the case, and provide the justification for this behavior. In the meanwhile, we will keep you posted with updates in this regard.
Good to know that your issue is sorted out by Aspose.Cells for .NET v8.4.0. Feel free to contact us any time if you need further help or have some other issue or queries, we will be happy to assist you soon.