No huge OP this time around, sorry.

How do you deal with multilingualism here on AG or on the internet in general?
Both as a native English speaker, and the issues that come from people not being native English speakers as well, and as non-native English speakers having conversations in English.
Which problems does it cause, are there any pros to either side as well?
Does your cultural background have any influence on how you communicate with others or how you behave on the internet, or do you consider the internet a cultural dead-space where your real life culture does not have any impact/it being drowned by the internet culture?
And, well, what is the most annoying part of speaking to someone that is/isn't a native English speaker?

How do you deal with multilingualism here on AG

If someone, say, posts in the Newcomers Forum in Spanish, "Hello people, I love this site. Who else lives in Mexico or speaks Spanish? Speak it here!" I might respond on their profile with, "Hola y bienvenidos a Armor Games. De acuerdo con las reglas, los foros son Inglés solamente, así que por favor traducir el texto antes de su publicación." It seems far more accomodating and effective than only having a mod lock/delete their thread 'without justification' in their eyes.

If you mean when a person attempts to use English and it's a mess, I tend to ignore the errors and seek out their message. Usually it's somewhat readable with the context of either what they quoted or the topic of the thread.

or on the internet in general?

Google translate to get an idea of what they're saying.

Which problems does it cause,

Often a few communication roadblocks, especially when one side uses extremely poor grammar, uses idioms/puns/slang/sarcasm, misspells words, or uses 1337/txt spk.

are there any pros to either side as well?

Not really.

Does your cultural background have any influence on how you communicate with others

Of course it does. Heck, there are many regional differences within English. For example, to "table" something in the US means to "set it aside for now" while in the UK it means to "address it immediately or work on it".

or how you behave on the internet,

Of course. We've all got different backgrounds. We've all got some stereotypes of others in different regions and other nations (which don't necessarily need to be negative: Canadians are friendly, Swiss are efficient, Asians are leet, etc., but can still cause misconceptions when attributed to specific individuals) whether we admit it or not. Tolerance and acceptance move us forward.

And, well, what is the most annoying part of speaking to someone that is/isn't a native English speaker?

Usually talking past each other due to perhaps a mistranslated word. Or being left out of the conversation entirely, but that goes both ways.

People are surprised that I can speak English. Lolz.

But apart from that, it's nothing major, since most of the peeps are from the States. And more Chinese people are trickling in, so I guess I'm not handicapped in any way. Nothing Google Translate can't solve if worse comes to worse.

I have talked to a few people in Spanish here, but I only know Spain's native Spanish for the most part, so occasionally I might say something a bit rude unintentionally to someone who lives in Central America.

Example?

In Spain, "coger"  means "to grab."

In Mexico, "coger" means "to kill."

Yes, there's a difference.

Yes, there's a difference.

Yeah, I have a friend on the internet who plays a game and gets paired with Mexicans a lot and he occasionally asks me to translate things, but more times than not it won't make sense because Cuban Spanish is slightly different from Mexican Spanish.

How do you deal with multilingualism here on AG or on the internet in general?

Well, all sites I visit are American/English, if there's a post/comment in another language that I don't understand, I'll most likely ignore it, but if it's about an interesting topic I'll paste it into Google translate. I rarely talk to people online in languages other than English, don't see the purpose if they can type/understand it fluently.
For everything else, Emp seems to have covered it nicely.

I rarely talk to people online in languages other than English, don't see the purpose if they can type/understand it fluently.

Well, this counts as well. Just because they are speaking English, it might not be their first language, and as such, are multi-lingual. Which I have seen leading to problems understanding subtle meanings sometimes, when you have not been raised into the language.
This is mainly my focus, not the "If someone talks to me in a language I don't understand", but rather the "everyone is speaking English, but not everyone have been raised with this language, how does this reflect communication".

I will blame it being rather late when I wrote the OP.

This is mainly my focus, not the "If someone talks to me in a language I don't understand", but rather the "everyone is speaking English, but not everyone have been raised with this language, how does this reflect communication".

It shows that the world is attempting to unite by using one language. Why it is English? No idea.

Of course it does. Heck, there are many regional differences within English. For example, to "table" something in the US means to "set it aside for now" while in the UK it means to "address it immediately or work on it".

Never once heard that saying? Mind using it in a example?

"everyone is speaking English, but not everyone have been raised with this language, how does this reflect communication".

In Chinese, the placing of the words don't really matter, and there are no verbs. Might affect my typing at times. But not much. I'm such a Twinkie.

Never once heard that saying?

It's more of a legal/business term.
Heeeeere's wiki!