Синхронный перевод подготовили на случай если публика не поймёт приглашённого докладчика.

It is the object, not the subject.

Why this can be confusing:

• перевод is masculine singular inanimate.
• In Russian, masculine singular inanimate nouns have the same form in the nominative and accusative.
• So синхронный перевод can look like either the simultaneous interpreting or simultaneous interpreting as an object.

How we know it is the object:

• The verb is подготовили = they prepared.
• That verb is plural, but перевод is singular.
• So синхронный перевод cannot be the grammatical subject here.

The sentence structure is basically:

• [They] prepared simultaneous interpreting...

Russian often leaves out this kind of they when the people involved are unknown, obvious, or unimportant.

This is a very common Russian pattern called an indefinite-personal construction.

подготовили literally means they prepared, but Russian often omits the subject when:

• the doer is unknown,
• the doer is not important,
• or it is obvious from context that some people did it.

So this sentence does not mean a specific they in the English sense. It is more like:

• They prepared simultaneous interpreting...
• or more naturally in English, Simultaneous interpreting was prepared...

Russian often prefers this active plural form where English might prefer a passive.

Here it means simultaneous interpreting, not written translation.

Why:

• перевод can mean both translation and interpreting in a general sense.
• But синхронный перевод is the standard term for simultaneous interpretation/interpreting.

So in this context:

• синхронный перевод подготовили means they arranged live interpretation for the event.

A natural English rendering would be:

• They arranged simultaneous interpreting...
• or Simultaneous interpretation was prepared...

It means in case.

So:

• на случай, если публика не поймёт... = in case the audience does not understand...

This expression introduces a possible situation that people want to be prepared for.

A few useful comparisons:

• если = if
• на случай, если = in case

So если by itself is a plain condition, while на случай, если adds the idea of preparation beforehand.

In standard written Russian, yes: it is normally written as на случай, если.

So the standard punctuation is:

Синхронный перевод подготовили на случай, если публика не поймёт приглашённого докладчика.

Why:

• если introduces a subordinate clause.
• After на случай, Russian normally puts a comma before если.

If you see it without a comma, that is usually:

• a typo,
• informal punctuation,
• or just careless writing.

For a learner, it is best to remember:

• на случай, если with a comma.

Because Russian is talking about a possible future result: the audience might fail to understand the speaker.

• поймёт is the perfective future of понять.
• It focuses on the completed result: understand / get what is being said.
• не поймёт = will not understand / may fail to understand

If you said не понимает, that would mean:

• does not understand right now,
• or generally does not understand

That is not the idea here. The sentence is about preparing interpreting in advance, in case at the event the audience doesn’t manage to understand the invited speaker.

This is an important difference between English and Russian.

In Russian, after если, you can use a future form when the meaning is future:

• если публика не поймёт = if the audience doesn’t understand / if the audience fails to understand

Russian does not have the same restriction as English here.

So:

• English: if the audience doesn’t understand
• Russian: если публика не поймёт

This is perfectly normal Russian.

Because публика is a collective noun. Grammatically, it is singular.

So Russian treats it like one group:

• публика не поймёт = the audience won’t understand

This is similar to English the audience, the crowd, the public:

• they refer to many people,
• but grammatically they are often singular.

That is why the verb is singular:

• публика не поймёт not
• публика не поймут

Because докладчика is in the accusative case.

The verb понять takes a direct object:

• понять кого? что? = to understand whom? what?

Here the audience may not understand the invited speaker, so speaker is the direct object.

Since докладчик is:

• masculine,
• singular,
• animate,

its accusative form looks like the genitive:

• nominative: докладчик
• accusative: докладчика

So:

• приглашённого докладчика = the invited speaker as the object of understand

It means the invited speaker or the invited presenter.

Breakdown:

• приглашённого = invited
• докладчика = speaker / presenter / lecturer giving a report

A докладчик is someone delivering a report, talk, or presentation, especially in a formal setting such as:

• a conference,
• a meeting,
• a symposium,
• an academic event.

So in this sentence, the idea is not just any speaker, but a guest speaker brought in for the event.

Russian word order is flexible, and here the sentence starts with the thing being highlighted:

• Синхронный перевод = what was prepared

Starting with it gives it more prominence. It is a natural way to present the important information first.

Possible alternatives are also possible, for example:

• Подготовили синхронный перевод...

But that version feels a bit more neutral in some contexts, while the original puts stronger focus on simultaneous interpreting itself.

So the original word order is natural and helps foreground the key measure that was taken.