I have a quick question, is it possible to have multiple programming languages for the Firebase Server in Cloud Functions?
Google Cloud Functions supports Node, Python, Go and Javathese days. For a full list, see the documentation on the Cloud Functions Execution Environment. Many other languages can be used, as they can be transpiled to one of the above.
When deploying your Cloud Functions through Firebase, the only supported languages is JavaScript and TypeScript on Node.js though.