Thanks for your inquiry.
No, you can not use such an approach. "TableStart:TableName" and "TableEnd:TableName" are the MERGEFIELDs to mark start and end of mail merge region. You can specify the "TableName" to be anything of your liking, but TableStart/TableEnd are not supposed to be changed as they are telling Aspose.Words API about mail merge region. Please have a look here for further details on mail merge regions as used in Aspose.Words for .NET at the moment.
Apart from this, we already have a new feature request (WORDSNET-3925) in our system for this purpose. This feature request is currently postponed due to other high priority tasks and work will start on it as soon as other, more prioritized issues are resolved. I am attaching this thread to the existing feature request so that its priority is raised and you could be notified as soon as the feature is complete and available.
Please note that the current feature request when completed will only allow us to use "RegionStart/RegionEnd" instead of "TableStart/TableEnd". Please have a look here to go through the already existing request for this purpose.
Hope this helps. Please do let us know if you have any more queries.