Hey if you wanna make private servers and add features to your emulator etc.
Then go with java
To make your cf-userlogin and signup etc.
Credit goes to TOXLP not me I asked a similar question and that is what he told me so learn java language (if you dont know programming langugaes this wont help you so learn programming language then you can start making private server)
I am also a beginner so i am starting to create a Trainer which is easier and after you master creating Trainers it will be easier to make private server (In my opinion)