Standard Translation

Whenever you open up a story, Standard Translation is in effect, even if you hardly notice it. Standard Translation is the simple phenomenon that no matter where in the multiverse a story takes place, the characters will speak the same language as the reader, even if in-narrative they are stated to be speaking another tongue.

The language the PPC deals with most often is the english language, but this convention exists for all written fiction, no matter the language. Thus, when fiction is translated into another language, it shouldn't be assumed that the canons within are suddenly fluent in that other language: they speak the language they always have, but have been translated to be accessible to readers.

Languages other than the standard translated language should probably be written out in proper form (if within the writer's capability) or expressed merely through narration. For example, with statements such as, 'he turned to his companions and began muttering in german/french/sindarin/martian/etc.' There are other acceptable ways of handling multiple-languages in-fic, but this way is the least distracting to the reader and the most widely used.

Notable Cases of the Standard Translation
Usually this principle of writing is so basic that nearly all readers assume it's in effect. Calling attention to it inthe story itself would be considered metafiction. But in some continuums, it might be an important point of note that the translation convention is in effect... and might even change the meaning of the story. Here are two notable examples that the PPC encounters frequently:
 * Stories set in Arda follow the language work of J.R.R. Tolkien, and the setting has a rich mix of languages. Characters should be assumed to be speaking their native languages (Westron, Quenya, Sindarin, Khuzdul, etc.) when they are the Point of View character, unless stated otherwise or obviously being bilingual. In third person omniscient, it probably should be assumed that Westron is the common language. Because of Tolkien's rich language work, it is entirely possible to actually write out other languages with the rules he set down, and there are people who are actually 'fluent' in his languages. Most of us, however, are not, and butchering these languages is a charge so common there's a whole unit for misuse of elven languages in the PPC.
 * Stories about canons that are set in non-english speaking countries should be assumed to have Standard Translation in effect. For example, a lot of anime is set in Japan (where most of it is made) and any characters that live in Japan probably speak Japanese, not English. Sometimes, in localization, Japanese dialects are swapped out for 'analogous' English ones. Fanfiction should try and match the canonical depiction as closely as possible in this case (the dialect might be a major feature of the character, localized or not) but it should not be assumed that a character is from Brooklyn because he speaks with a Brooklyn accent through localization. (See: Yu-Gi-Oh!'s Joey Wheeler/Katsuya Jounouchi)

Variating from Standard Translation
Deviating from the model is not always bad. For example, as above, J.R.R. Tolkien wrote whole languages to more fully realize Arda. However, many writers deviate from the standard translation in ways that call attention to that choice, too. Some common variations:

Font as Language

 * Some stories will try and use font, or type weight, to stand in for a language that is different from the standard translated language. For example, if it's assumed that characters are speaking Westron, a character speaking in Sindarin might be italic or a different font. This method allows readers to understand what is being spoken in both languages... but may ignore the fact that the reader is viewing the story from a certain point of view that may not know the language in question.

Gibberish as Language

 * Other languages are sometimes rendered as gibberish, whether in alphanumeric characters ("ASDIJDIFSDUWD") or as symbols ("#*(#&@&#@#&!*@#!"). This might be used to express a language that does not have sounds that a human could produce, or it may simply be a stand-in for a language the author does not know. In the latter case it is often disruptive because anybody with eyes knows that there is no language composed of "ASDFASDFASDF."

Dialect as Language

 * Sometimes, a writer will substitute an actual language with a dialect or accent. Such as, their french speaking character merely speaks with a phonetic french accent and other characters treat that as french. This can get a little silly, especially when readers are faced with 'olde English.'

Errors of Standard Translation
Not all stories really understand how to make the assumed-standard language in dialogue make sense. Here are some common errors, all of which can be charges when encountered in a badfic:

Inserting Superfluous Language

 * If a character is already assumed to be speaking a foreign language (even if you are reading the story in English) then it's also assumed that all of their words are translated. It does not make sense for non-specific words to NOT be translated, or to be added back in after translation. For example, if a character is assumed to be speaking Japanese, then that character wouldn't call someone a 'baka,' they would call someone an 'idiot.' Not only is this terrible grammar in both languages, but also is somewhat meaningless. This is a common feature of Fangirl Japanese.

Unlikely Language Mastery

 * If a writer is not careful, they can forget which language is supposed to be the standard one. This can make characters that would otherwise not be able to converse, mysteriously speak the same language. This is commonly seen in self-insert or 'character falls into continuum' fiction: when a character passes from outside the fourth wall, to inside the fourth wall. Outside the fourth wall, the translation is in effect because the medium they are experiencing the story through is made for the audience's language. However, inside the fourth wall, this is not true. Without a proper explanation, this leads to such confusion as an English-speaking character being able to converse with a Westron-speaking character without difficulty. In these stories, is English the standard language, or is Westron the standard language?

Web Translator Language

 * When faced with characters that speak other languages than the local standard, some authors will try and actually include that language in their writing... even if they don't speak it at all. Web translators are often used to automatically convert English to another language... albeit most often imperfectly. Figures of speech are famously difficult to translate this way, and can lead to hilarious or grammatically unsound (or both) statements in other tongues. Web translators also exist for some fictional languages, though they often don't actually translate the statement in question but parse the syllables and convert them into other sounds... ones that may superficially resemble the language in question but not actually mean anything. See grelvish and/or coney-grelvish.

Standard Translation and the PPC
PPC spin-offs handle translation in various ways. In some spin-offs, agents have universal translators, which if lost can prevent the agents from understanding canon characters. In other spin-offs, because the agents can look at the Words, they have a connection to the fourth wall of a fanfic, allowing them to experience the canon world with the translation in place: able to understand and be understood by OCs and canon characters alike.

But most spin-offs simply don't call attention to the standard translation unless it's marred by errors, because it is healthiest when working in the background and not thought about. It can be assumed that in order to do their jobs, PPC staff would have to be able to understand canon characters somehow, so it's not as much of a big deal as say, an OC wandering around Arda with no reason to understand the local language whatsoever.