Ni estus sidintaj ĉirkaŭ la tablo pli longe, se la kelnerino ne estus alportinta la fakturon tiel frue.

In Esperanto, a contrary-to-fact if sentence often uses -us in both the main clause and the se clause.

English says:

• we would have sat
• if the waitress had not brought

Esperanto can express both ideas with estus + participle:

• Ni estus sidintaj
• se la kelnerino ne estus alportinta

So this is a normal Esperanto way to show an unreal past situation. Esperanto does not have a separate finite verb form exactly like English had brought, so it often uses this compound pattern instead.

Estus sidintaj is more explicit. It clearly means would have sat or would have been sitting earlier in that hypothetical past situation.

The simpler sidus can sometimes work if the context already makes the time clear, but it is less precise. It can feel more like would sit or would be sitting.

So:

• sidus = simpler conditional
• estus sidintaj = explicitly counterfactual past

The sentence uses the fuller form to make the past-time relationship very clear.

-int- is the marker for the past active participle.

It gives the idea of having done something.

So:

• sidinta = having sat
• alportinta = having brought

When combined with esti, it helps form compound expressions such as:

• estus sidinta = would have sat
• estus alportinta = would have brought / had brought in this kind of conditional context

So -int- is the key part that shows the action is already completed relative to the hypothetical situation.

Participles in Esperanto behave like adjectives, so they agree with the noun or pronoun they describe.

• sidintaj refers to ni, which is plural, so it takes -j
• alportinta refers to la kelnerino, which is singular, so there is no -j

Breakdown:

• sidintaj = sid- + int + a + j
• alportinta = alport- + int + a

A useful comparison:

• Mi estus sidinta = I would have sat
• Ni estus sidintaj = We would have sat

Also, Esperanto adjectives and participles do not change for gender, so the difference here is about number, not masculinity or femininity.

Because la fakturon is the direct object of alporti.

The waitress is the one doing the action, and the bill is the thing being brought. In Esperanto, direct objects take -n.

So:

• la kelnerino = subject
• la fakturon = direct object

That is why it is fakturon, not fakturo.

Here ĉirkaŭ la tablo describes location: where the people were sitting.

It means they were sitting around the table, not moving the table somewhere, and tablo is not the direct object of the verb.

So plain ĉirkaŭ la tablo is exactly what you would expect here.

A simple way to think of it:

• sidis ĉirkaŭ la tablo = sat around the table

The phrase is just a prepositional phrase showing place.

Because longe is an adverb, and it modifies the action of sitting.

The sentence is talking about how long they would have sat, so Esperanto uses an adverb:

• pli longe = longer

By contrast, longa is an adjective and would need to describe a noun:

• pli longa restado = a longer stay
• pli longa tempo = a longer time

So in this sentence:

• sidus/sidintaj pli longe = would have sat longer

They are close, but not the same.

• tiel frue = so early, that early
• tro frue = too early

Tiel points to degree, often with an implied consequence. That fits this sentence well: the bill came so early that they did not stay longer.

Tro adds a judgment of excess: earlier than was acceptable or appropriate.

So:

• tiel frue = focuses on the degree
• tro frue = focuses on excessiveness

In many contexts, both could make sense, but they are not identical.

In Esperanto, ne normally comes before the verb or verb phrase that it negates.

So:

• ne estus alportinta = had not brought / would not have brought

This is the standard placement. It negates the whole verbal idea.

If you moved ne somewhere else, the sentence could sound odd or shift the emphasis. For a learner, the safest pattern is:

• ne
  • verb

So this sentence follows the normal rule.

It is made from:

• porti = to carry
• al- = toward, to

So alporti literally means to carry to, and in natural English that is usually to bring.

This kind of word-building is very common in Esperanto. Once you know the parts, many words become easier to understand.

For example:

• porti = carry
• alporti = bring
• forporti = carry away, take away

Kelnerino means waitress.

It is built from:

• kelner- = waiter/server
• -in- = female
• -o = noun ending

So:

• kelnero = waiter
• kelnerino = waitress

This is a very common Esperanto pattern:

• patro = father
• patrino = mother
• instruisto = teacher
• instruistino = female teacher

So even if you have never seen kelnerino before, the ending -in- gives you a strong clue that it refers to a female person.

Yes. Esperanto word order is fairly flexible, so you could also say:

Se la kelnerino ne estus alportinta la fakturon tiel frue, ni estus sidintaj ĉirkaŭ la tablo pli longe.

That means the same thing.

The difference is mainly emphasis and flow:

• starting with Ni estus... puts the result first
• starting with Se la kelnerino... puts the condition first

Both are correct.