I like the tone of your post and the use of the word “incidents”.

As for your question, well it’s like pretty much everything in life, it depends. Is it fine to greet (not wish***) someone with a “Bonjour”? Well, yes, it’s fine. Is it correct French? Not really. That’s meant to be used during days, and “Bonsoir” would have been more appropriated in that particular case.

*** : Let’s now jump to little explanations ; “Bonsoir” (or “Bonjour”), is only meant to greet. People tend to think it’s also used as a wish (due to the literal translation that would be something like “Good day!”), when it’s only used as a greeting. People never really mean wishing people a good day or night saying those things in France. Hope I helped out!

EDIT : Regarding the ‘uneasy’ part that I forgot to talk about, well, as Simon said, it might make someone that said “Bonjour”, and that you replied “Bonsoir” to, believe that you’re correcting him/her. But that’s kind of relative. I’ve been in situations where people have been laughing because it was a mistake or something else.

When someone says bonjour at night and you reply bonsoir, it can make them feel uneasy because it may sound like you are correcting them. Of course it depends on the tone of your voice and many micro-details, especially if you insist on bonsoir like « you mean "bonsoir" I suppose ».

This often happens:

« -Bonjour !

-Bonsoir !

-Euh oui, bonsoir. »

Salut is mainly for your friends, your family, people you meet at a party even if you don’t know them, etc. – in general, if you say tu to someone you can say salut, but if you say vous you should avoid salut – I suppose it’s rather equivalent to English hi.

To me it’s fine to say bonjour instead of bonsoir (not the contrary though), and it’s fine to reply bonjour or bonsoir too. Personally I reply bonjour if the person said bonjour at night, not to make them uncomfortable.

An awkward thing often happens: you are mentally ready to hear and say bonjour but the person says bonsoir so you mess up and reply something like bonjoir.

It is not wrong to say Bonjour at night even if it is more frequent to say Bonsoir than Bonjour after, let’s say, 7pm. There is no strict rule that defines when it is time to say Bonsoir, and it is not mandatory to say Bonsoir even during the night.

At the opposite, it is inappropriate to say Bonsoir during the day. It is very uncommon and usually shows that you’re a bit lost after a sleepless night for example.

Saying Bonsoir when someone said Bonjour isn’t inappropriate as long as the tone doesn’t have an implicit meaning as Simon said. If you want to be sure to stay polite, just answer what you were greeted with.