When you congratulate someone for something you praise them for an achievement, e.g. "I'd like to congratulate the staff for their good job". According to Google NGram Viewer congratulate on is a lot more frequent than congratulate for, but the latter is used nevertheless. To answer your question, both sound natural to me.
"We congratulate you to this most important result " - I came across this usage in a speech of fair importance, hosted on a distinguished portal. This speech may not have been delivered in English,...
word usage - Congratulate "to" - How correct is this? - English ...
Birthday Congratulations @Levi I would say that we can congratulate Sb. on their birthday, but we don't actually say "congratulations".
When I was young, a workmate convinced me that there was indeed a word which described the behaviour of someone who would congratulate themselves for behaving the way a person normally ought to, an...
For instance, I have to congratulate a friend on his marriage after one month. P.S. I know that we can always keep it simple and convey the most, but I am just curious to know if there is any word equivalent to 'anniversary' but for the time period of one month.