Из-за задержки поезда мы не успели на семинар.

Из-за means because of, due to, or as a result of. It introduces the reason for something, usually with a somewhat negative or unwanted cause.

So in this sentence:

Из-за задержки поезда... = Because of the train delay...

A useful thing to remember is that из-за is followed by the genitive case.

Because of case.

• из-за requires the genitive
• задержка becomes задержки
• поезд becomes поезда

Here the structure is:

• из-за задержки = because of a delay
• задержки поезда = the delay of the train / the train delay

So поезда is also in the genitive because it depends on задержки: it tells us whose delay it was.

Russian often expresses X of Y by putting Y in the genitive case.

So:

• задержка поезда = the train's delay / the delay of the train

This is the most normal and direct way to say it.

A form like поездная задержка would sound more like railway-related delay or an adjectival expression, not the natural everyday way to say the train’s delay in this context.

Успели is the past plural form of успеть, which usually means:

• to manage to do something
• to make it in time
• to be in time for something

In this sentence, не успели на семинар means:

• we didn’t make it to the seminar in time
• we were too late for the seminar

So this is not just a basic past tense of to be late. It carries the idea of failing to make it in time.

Because успеть на + event/transport/place is a common Russian pattern meaning to make it to something in time.

Examples:

• успеть на поезд = to catch the train / make it to the train in time
• успеть на урок = to make it to class in time
• успеть на семинар = to make it to the seminar in time

Here семинар is in the accusative case, but since it is a masculine inanimate noun, the accusative looks the same as the nominative:

• nominative: семинар
• accusative: семинар

It usually means they did not make it in time for the seminar. Depending on context, that could mean:

• they missed the beginning
• they arrived too late to attend properly
• they missed it altogether

The phrase itself does not always specify exactly how much was missed. It only tells you they failed to arrive in time.

Yes, Russian often omits subject pronouns when they are clear from the verb form.

So both of these are possible:

• Из-за задержки поезда мы не успели на семинар.
• Из-за задержки поезда не успели на семинар.

The version with мы is a bit clearer and can add slight emphasis: we didn’t make it in time.

Since успели is plural, the listener already knows the subject is we or they, so context matters if the pronoun is omitted.

Yes, Russian word order is flexible.

The given sentence:

Из-за задержки поезда мы не успели на семинар.

is very natural because it starts with the reason, then gives the main result.

Other possible orders include:

• Мы не успели на семинар из-за задержки поезда.
• На семинар мы не успели из-за задержки поезда.

These all mean roughly the same thing, but the emphasis changes:

• starting with Из-за задержки поезда highlights the cause
• starting with Мы highlights the people
• starting with На семинар highlights what they failed to make it to

Успеть is perfective.

That matters because the sentence is about a completed outcome: whether they made it in time or not. Russian uses the perfective here because the result is important:

• успели = they managed / they made it in time
• не успели = they didn’t manage / they didn’t make it in time

The imperfective partner is успевать, which is used more for repeated action, process, or general ability in context.

For example:

• Я всегда успеваю на работу. = I always make it to work on time.
• Мы не успели на семинар. = We didn’t make it to the seminar in time.

Usually yes, or at least it often suggests an undesirable cause.

That is why it fits very well here:

• из-за задержки поезда = because of the train delay

A delay is obviously something inconvenient, so из-за sounds natural.

For more neutral causes, Russian often uses expressions like из-за, из + noun, от, or потому что, depending on the structure and meaning. But in everyday usage, learners should strongly associate из-за with negative or problematic reasons.

Not very naturally.

A word-for-word breakdown is something like:

• Из-за = because of
• задержки = delay
• поезда = of the train
• мы = we
• не успели = did not manage to be in time
• на семинар = for/to the seminar

Natural English translations would be:

• Because of the train delay, we didn’t make it to the seminar in time.
• We were late for the seminar because of the train delay.
• Because the train was delayed, we missed the seminar.

So it is better to understand the Russian structure, but translate it into normal English rather than word for word.