Cloning an altcoin is trivial and doesn't require knowledge of c/c++ because all the code is already written.
Just tweak some parameters and you have a brand new coin.
True developmnet, specifically mastering it, doesn't require knowledge of any specific language. The language
is just a tool and the job usually determines the appropriate tool to use.
Cryptography, multithreading, networking, gui, distributed processing, etc are the programming skills you need
to master altcoin development.
Good advice