Replacing VBScript with c#

You should take a look at the "Vault Application Framework".  This framework allows you to build "vault applications" using C# and deploy them into the vault.  These vault applications can contain the items that you would historically have used VBScript for such as property value calculations, validations, event handlers, state actions, etc.

This is a good reference: The Vault Application Framework

To get started download the Visual Studio add-in from the marketplace.  This will give you some templates inside Visual Studio that you can use to create projects: The Vault Application Framework Visual Studio Template

There is also a set of content on the M-Files Academy which details how to build these sorts of applications.  You should have access to this but if not then reach out to either your partner (if you're a customer) or your partner manager (if you're a partner).

Thanks Craig

You can also check a VAF already written and working; property calculator It can replace most of the calculation codes written in vbs