You're not alone. The more experience I get, the more I feel that specifics in a language are a commodity, but what you do with that language is what matters.

Those abstractions, identifying problems, talking with peers, deciding the next step, etc. The language is not the problem, you will learn it.

With time I got to know more core concepts but I don't know the syntax of whatever language the interviewer's company is using. It is nice to find people interviewing you who care more about what you're trying to say than the syntax.