A régi dokumentum hibás, ezért letöltöm az új változatot.

In Hungarian, the verb to be is usually omitted in the present tense, third person when the predicate is a noun or adjective.

So:

• A régi dokumentum hibás = The old document is faulty

But in other persons or tenses, van / volt / lesz etc. appear:

• Én hibás vagyok = I am at fault
• A dokumentum hibás volt = The document was faulty
• A dokumentum hibás lesz = The document will be faulty

So the missing is is completely normal here.

A and az are just two forms of the same definite article: the.

The choice depends on the sound that follows:

• a before a consonant sound: a régi dokumentum
• az before a vowel sound: az új változatot

So:

• a régi... because régi begins with r
• az új... because új begins with a vowel sound

The ending -ot marks the direct object. This is the accusative case in Hungarian.

So:

• változat = version
• változatot = version as the thing being downloaded

In this sentence, the thing being downloaded is the new version, so Hungarian marks it:

• letöltöm az új változatot

This is very common in Hungarian: direct objects usually get -t in some form.

More examples:

• dokumentum → dokumentumot
• könyv → könyvet
• filmet nézek = I’m watching a film

Because Hungarian uses a special verb conjugation when the verb has a definite object.

Here the object is:

• az új változatot = the new version

That is definite, so the verb uses the definite conjugation:

• letöltöm = I download it / I am downloading the definite thing

Compare:

• Letöltök egy változatot. = I’m downloading a version.
  Indefinite object → letöltök
• Letöltöm a változatot. = I’m downloading the version.
  Definite object → letöltöm

So the -m ending here is a clue that the object is definite.

Le- is a verbal prefix. In many verbs, prefixes modify the basic meaning.

Here:

• tölt can mean fill / load
• letölt means download

The prefix le- often has a sense like down, which matches the idea of downloading.

A useful thing to know: Hungarian verbal prefixes can move around.

For example:

• Letöltöm a fájlt. = I download the file.
• Nem töltöm le a fájlt. = I’m not downloading the file.
• Le akarom tölteni a fájlt. = I want to download the file.

So in the base sentence, letöltöm is a prefixed verb in its normal neutral position.

Because Hungarian adjectives usually do not agree with the noun the way they do in many Indo-European languages.

So you simply get:

• régi dokumentum = old document
• régi dokumentumok = old documents
• az új változatot = the new version (object form)

The adjective itself stays the same when it comes before the noun.

This is different from languages where adjectives change for gender, number, or case. Hungarian has no grammatical gender, and attributive adjectives are usually unchanged.

A useful comparison:

• az új változatot = the new version
• az újat = the new one

When the noun is omitted and the adjective stands on its own, then it can take endings.

Ezért means therefore, for this reason, or that’s why.

It introduces the result/consequence of what came before:

• A régi dokumentum hibás, ezért letöltöm az új változatot.
• The old document is faulty, therefore I download / am downloading / will download the new version.

A very useful comparison:

• mert = because
  introduces the reason
• ezért = therefore / that’s why
  introduces the result

Compare:

• Letöltöm az új változatot, mert a régi dokumentum hibás.
  I’m downloading the new version because the old document is faulty.

• A régi dokumentum hibás, ezért letöltöm az új változatot.
  The old document is faulty, therefore I’m downloading the new version.

It can mean any of those, depending on context.

Hungarian present tense is often broader than English present tense. It can express:

• a habitual action: I download
• a current action: I’m downloading
• a near-future action: I will download

In this sentence, the most natural English translation is probably:

• The old document is faulty, so I’m downloading the new version.

But in another context it could also mean:

• ...so I’ll download the new version.

Context decides which English tense sounds best.

Yes, Hungarian word order is flexible, but it is not random. It often reflects topic and focus.

The version in your sentence is a normal, neutral order:

• letöltöm az új változatot

This is fine when you are simply stating what you are doing.

But you can change the order for emphasis:

• Az új változatot töltöm le.
  = It’s the new version that I’m downloading.

Notice that when another element is strongly focused, the verbal prefix often moves away from the verb:

• neutral: letöltöm
• focused object: az új változatot töltöm le

So word order in Hungarian often tells you what is being emphasized.

Yes:

• A = the
• régi = old
• dokumentum = document
• hibás = faulty / incorrect / defective
• ezért = therefore / for this reason
• letöltöm = I download / I’m downloading / I will download it
• az = the
• új = new
• változatot = version
  • direct object ending

A more literal structure would be:

• The old document faulty, therefore I-download-the new version

Natural English:

• The old document is faulty, so I’m downloading the new version.

Hibás usually means faulty, incorrect, erroneous, or defective. It suggests that something has an error or flaw.

So for a document, hibás can mean:

• it contains mistakes
• it is incorrect
• it is the wrong or flawed version

By contrast, rossz is broader and often just means bad.

Compare:

• A dokumentum hibás. = The document is incorrect / faulty.
• A dokumentum rossz. = The document is bad.

In this sentence, hibás is more precise because it explains why a new version is needed.