Sem a szomszéd, sem a közös képviselő nem egyeztetett velem.

It means neither ... nor ....

So:

• Sem a szomszéd, sem a közös képviselő ...
  = Neither the neighbor nor the building representative ...

This is a very common Hungarian pattern for linking two negative alternatives.

Hungarian normally uses negative concord, which means multiple negative elements appear together in the same sentence.

So the standard pattern is:

• sem X, sem Y nem + verb

Literally, Hungarian uses both the sem ... sem ... structure and the negative verb form with nem.

So:

• Sem a szomszéd, sem a közös képviselő nem egyeztetett velem.

This is the normal, correct Hungarian way to say Neither the neighbor nor the building representative consulted/coordinated with me.

Because sem does not replace the definite article. It just adds the meaning neither/nor to the noun phrase.

So:

• a szomszéd = the neighbor
• a közös képviselő = the common/building representative

After sem, the noun phrase usually keeps its normal article if it would normally have one:

• sem a szomszéd
• sem a közös képviselő

This is completely normal Hungarian.

This is a specifically Hungarian housing/apartment-building term.

A közös képviselő is the person who represents the apartment building or condominium community in shared matters. Depending on context, in English this could be something like:

• building representative
• property manager
• condo association representative
• HOA-type representative

It does not usually mean common representative in natural English, even though that is the literal meaning.

The verb egyeztet can mean things like:

• to coordinate
• to consult
• to discuss and align details
• to clear something with someone
• to arrange something by consultation

So egyeztetett velem means roughly:

• consulted with me
• coordinated with me
• discussed it with me beforehand

The exact English translation depends on context, but the core idea is that they did not talk things through or coordinate with me.

Because the Hungarian form meaning with me is irregular.

The ending for with is -val / -vel, but personal pronouns do not use the regular pattern here. Instead, they have special forms:

• velem = with me
• veled = with you
• vele = with him/her/it
• velünk = with us
• veletek = with you plural
• velük = with them

So:

• egyeztetett velem = consulted/coordinated with me

You simply have to learn velem as the correct pronoun form.

Egyeztetett is:

• past tense
• third person singular

So it means he/she/it consulted/coordinated.

The dictionary form is egyeztet. In the past tense, third person singular often gets a -tt-type ending, so:

• egyeztet → egyeztetett

That is why you see the doubled t. It is not a typo.

Because with sem ..., sem ... plus two singular nouns, Hungarian usually uses a singular verb.

So:

• Sem a szomszéd, sem a közös képviselő nem egyeztetett velem.

This is the normal pattern, similar in idea to English Neither the neighbor nor the representative consulted with me.

Hungarian is treating them as separate excluded possibilities: not the neighbor, and not the representative either.

If the nouns themselves were plural, then the verb would also be plural.

Hungarian word order is flexible, but it is strongly connected to focus and emphasis.

By putting Sem a szomszéd, sem a közös képviselő at the beginning, the sentence highlights the two people who did not do the action.

So the structure is:

• Sem a szomszéd, sem a közös képviselő = neither the neighbor nor the representative
• nem egyeztetett = did not consult/coordinate
• velem = with me

This order is very natural and clear. It foregrounds the negative contrast.

Yes. Se and sem are closely related, and both can mean not ... either / neither depending on context.

However, in a structure like this, sem ..., sem ... is very common and sounds full and standard:

• Sem a szomszéd, sem a közös képviselő ...

You will also hear se in many everyday sentences, but here sem is a very natural choice.

Yes, there are other possible phrasings, but this version is standard and natural.

For example, you may also see:

• A szomszéd sem, a közös képviselő sem egyeztetett velem.

This also means roughly The neighbor didn’t consult with me either, and the building representative didn’t either.

The original version:

• Sem a szomszéd, sem a közös képviselő nem egyeztetett velem.

is a clean, textbook-style way to say Neither the neighbor nor the building representative consulted with me.