A common context in which it's used is in the idiom "herald a new era" - here's a search: https://www.google.com/search?q="heralds+a+new+era" which shows that it's pretty common.
It's also used in the names of many newspapers around the world: https://en.wikipedia.org/wiki/Herald_(newspaper)
There's also the Christmas carol, "Hark! The Herald Angels Sing": https://en.wikipedia.org/wiki/Hark!_The_Herald_Angels_Sing
But I suppose if you don't already know the word "herald" you might just put that down to weird religious language.
It is a small sample, but you could ask your family and friends.
Plus, I still prefer something that most if not all people know: news-teller over herald, so I would have translated it to that.
You could go around and ask people if they know the meaning of "herald". I did, and many people did not know, but "news-teller" is definitely obvious, and as I have previously said in two other comments: while "news-teller" is not a standard or formally recognized English word, it is likely that many English speakers would still recognize and understand its meaning, more so than "herald", in my opinion, and in accordance to my experiences.
Language evolves. :)
It is unfortunate that meaningful discourse often suffers when individuals form hasty judgments based solely on the initial few words of a comment, or when they make assumptions and jump to conclusions without fully considering the underlying content and intent. In my experience, I frequently encounter down-votes in such situations, which I find quite disappointing, especially when these down-votes occur without any accompanying explanation or constructive feedback. Such superficial engagement diminishes the quality of discussion and discourages thoughtful contributions, IMO.
TL;DR: Down-voting without explanation is quite frustrating. People hastily form misguided judgments on content they haven't fully understood, think "I don't like it" and down-vote without consideration (and any form of feedback or constructive criticism).
Check out my other replies if you are interested[1].
In any case, language evolves. :)
[1] https://news.ycombinator.com/item?id=44845717, https://news.ycombinator.com/item?id=44845575
A more idiomatic translation would be “reporter”.