There will be different perspectives on this, below are few things which should help to be a good test automation engineer.
Taking a real life example, we all love to travel and explore new places. Given a chance with some million dollars, I could rather do a world tour. But does it mean I know all the languages people speak round the world? Will language barrier stop me travelling around world? Never! In-fact whenever we plan any tour we never think of this as hurdle. Rather we are more exited to explore new place, experience new people and live their life for some time.
Looking from other perspective, was it easy for alien PK, protagonist from PK movie, to sustain on earth until he learns language that people here understood. Now here is the actually difference, was the language barrier for him? Not at all, once he learnt the behaviour of people on earth, things became lot easy and eventually he did learn language for communication.
Now relating all this to automation, if we are conceptually expertise in domain of product and ways of automation, we are no more an alien to this test automation world. There will be a jittery when you move into different teams using different languages to automate. But being conceptually strong will speed you up even in new team.
Again, when we talk about languages, every language will be based on same concepts has per their type (Procedural, Object Oriented, Scripting and so on…). So again having conceptual expertise while learning language will help here as well.
Sometimes, it our learning pattern which makes us strong in language but less expertise in concepts. In this work process of agile, continuous delivery we are tend to focus more on delivering as early as possible). So, when we learn any new language, we try to get the syntaxes and reach the expected output. And then later on this becomes a blocker for us if we are required to work in any different language.
Being conceptually strong will be a big boost to our confidence at anytime, even if placed in any team which uses technologies which we are un-discovered for us. We learn lot, but this little tweak in the way we learn will take us much more higher and make our daily things very easy for us.
So if you are new to testing or test automation or planning to learn more in any area, try to get expert in concepts. Technologies will keep on changing and you have to move with new technologies but with strong conceptual expertise.