I would be more concerned that you spent the last X years only using one language, no matter how esoteric it is. If I had to hire someone who has not used the main language(s) in my company's stack, I would prefer someone who spent the last X years working in multiple languages, who should be more likely to learn our language(s) quickly.
From a career perspective, working in one single language seems far more limiting than focusing on some esoteric language(s). I don't even understand how it's possible to spend five years in one language. On a day to day basis I use JavaScript, bash, and python.
Focusing on only C++ or Java or one of the "mainstream" languages seems just as "bad" as focusing on one esoteric language. Try to pick a job where you are exposed to multiple languages/paradigms on a daily basis.
I was extremely worried when I started reading your comment - I've been working on python since I got out of university. Reading the rest of the comment gave me relief - I also used Javascript, PostgreSQL, MySQL, CSS, Sass, Less, React, Angular, bash, Lua, C, GLSL. Phew.
From a career perspective, working in one single language seems far more limiting than focusing on some esoteric language(s). I don't even understand how it's possible to spend five years in one language. On a day to day basis I use JavaScript, bash, and python.
Focusing on only C++ or Java or one of the "mainstream" languages seems just as "bad" as focusing on one esoteric language. Try to pick a job where you are exposed to multiple languages/paradigms on a daily basis.