UiPath does not allow mixing VB.NET and C# in the same project, the language is fixed at creation.
To use C#, you need to recreate the REFramework in C# and migrate workflows there.
The language (C# or VB.NET) doesn’t impact deployment to Orchestrator for attended or unattended bots.
UiPath compiles projects into packages, and robots execute them the same way regardless of language.