[reviewersman]

Is there any benefit, aside from getting a niche job, in learning older languages like FORTRAN or COBOL?

[callmevirgin]

better learn C, C++/ CPP, or Java. start doing leetcode questions and grind data structure. don't waste time learning irrelevant stuffs

[dragoncochon]

I think like you mentionned that the only benefit is to get a niche job in defence or bank system where these developers are paid a lot.
I am afraid that you may not find a lot of help on internet if you struggle on these languages and you will need to debug a lot of stuff on your own.