[Michelle]

*waves magical proofreading wand here instead of the google doc because I took way too long there*

These rules apply everywhere in Mesalia Roleplay: in game, on the forum, on official Mesalia Skype chats, etc.

So why is it 'Roleplay' here and not 'RP', when later in the rules it refers to roleplay as 'RP'. I'm not telling you to change it to 'RP', I'm just telling you to pick one and stick with it; are we assuming the reader knows 'RP' abbreviates 'roleplay' or not?

Listen to staff, do not lie or argue with instruction.

This is a comma splice, meaning it's not grammatically correct.
Correct alternatives:
'Listen to staff; do not lie, or argue with instructions.'
'Listen to staff. Do not lie, or argue with instructions.'
'Listen to staff, and do not lie or argue with instructions.'

However, you may file a complaint or report them to the admin.

Wait, why are these separate options? What is the difference? Sounds like it's worth explaining further.

Staff works hard to make Mesalia a place for everyone to enjoy, but the rules are there for reasons and they have to enforce them.

This... is very common-sensical. Do people really not understand this to the point where it needs to be said? >.< If so, let me fix the grammar and make it more succinct:
'The staff work hard to make Mesalia an enjoyable place for everyone, but the rules exist for a reason, and they must be enforced.'
If not, I'd remove it entirely.

Griefing includes but its not limited to willful destruction to the setting, creation of obstructive, offensive or distracting structures, repeatedly killing players out-of-character, tampering with in-character inventory and RP’s, and any other behavior or action that is harmful to the server or the players.

'Griefing includes but is not limited to: willful destruction of the setting; creation of obstructive, offensive or distracting structures; repeatedly killing players out-of-character; tampering with in-character inventories and RPs; and any other behavior or action that is harmful to the server or the players.'
(Fixed spelling, wording, and punctuation).

This also extends to the intention to harm the server, this is one of the most serious offences against the server and will result in an instant permanent ban and blacklisting for all parties involved.

'Intention to harm the server' is very vague. Do you mean Dos/DDos attacks, or just general intention to grief?
Also this is a comma splice. Correct alternative:
'This also extends to the intention to harm the server; this is one of the most serious offences against the server, and will result in an instant, permanent ban and blacklisting for all parties involved.'

The RP is in English and we require all of the communications within the community to be in English. In order to effectively participate in this community you must be able to speak English and use reasonably correct grammar and spelling, from your application, the RP, to out-of-character discussions.

This is a slight trainwreck. The second sentence is extremely clunky, and the first one is almost redundant; it doesn't really add any new information (and just makes things seem confusing/vaguely intolerant of other languages). I wrote an alternative thing to explain this rule:
'We require all of the communications within the community to be in English. This is not only to ensure you are understood, but it is also for regulation purposes (i.e. so the staff know you are not breaking rules). If you do need to say something in another language, you are to provide a correct translation alongside it. This rule also extends to the use of grammar and spelling; these must be to a reasonably correct standard, regardless of whether it is out-of-character or in-character, or where it is written.'

I'd also put this rule before the smart-arse one; maybe after the PG 13 one. Idk, it just seems out of place when it comes after a slightly informal, crassly-worded rule (which is crassly-worded for effect).

Also,

smart-arse

I know I wrote this, so of course it's spelt 'arse' since I write in British English. But the rest of this section is written in American English, so I would change this to 'ass'. I don't really care what version of English is used; just pick one and be consistent.

Okay, that's all I got.

EDIT: If you read this and aren't staff, you might realise that I am very lenient on grammar and spelling when WLing.