For Erlang I would say that the hard part is not the language itself (maybe a bit because it is influenced by prolog) but because of the mental model. Using concurrency and parallelism as core concepts of the language and understanding that you don’t need a lot of the external tools you would with the more mainstream languages is what’s hard imo.
AI in the product name or description makes sure that there is not a single chance I buy it.
It makes filtering products and companies easier