Depois de reler o rascunho, percebi que o tema estava bom, mas o resumo estava longo demais.

Both are possible, but they work a little differently.

• Depois de + infinitive is a very common way to say after doing something.
  • Depois de reler o rascunho, percebi...
• Depois que + finite verb is also correct:
  • Depois que reli o rascunho, percebi...

The version with depois de + infinitive is often a bit more compact and elegant in writing.

Reler means to reread.

It is formed from:

• ler = to read
• prefix re- = again

So:

• ler = read
• reler = reread

In the sentence, reler o rascunho means to reread the draft.

Because Portuguese often drops subject pronouns when the verb form already makes the subject clear.

• Percebi already means I noticed / I realized
• So eu percebi is possible, but eu is unnecessary unless you want emphasis or contrast

Examples:

• Percebi que... = I realized that...
• Eu percebi que... = I realized that... (more emphasis)

This omission is very normal in Portuguese.

Here, percebi is closest to realized or noticed.

Perceber can mean:

• to notice
• to realize
• to perceive

In this sentence, the speaker reread the draft and then came to a conclusion about it, so I realized is often the best fit in English.

Because perceber que... means to realize/notice that...

So the structure is:

• percebi que o tema estava bom
• I realized that the topic was good

This is extremely common in Portuguese:

• Achei que... = I thought that...
• Vi que... = I saw that...
• Notei que... = I noticed that...
• Percebi que... = I realized that...

Just like in English, que introduces the following clause.

Because estava presents these qualities as a state or evaluation at that moment.

• o tema estava bom
• o resumo estava longo demais

This sounds like the speaker is assessing the draft and describing how things seemed when rereading it.

Why not era?

• Era can sound more general or categorical
• Estava sounds more like was in that state at that point

Why not foi?

• Foi usually sounds more completed or definite
• It is less natural for this kind of ongoing descriptive evaluation

So estava fits very well with comments about the quality or condition of parts of a text.

In this context:

• tema = the topic, theme, or subject
• resumo = the summary, and in some academic contexts possibly the abstract

So the speaker is saying that the main topic was fine, but the summary section was too long.

A learner should know that tema does not always mean theme in the literary sense; very often it simply means topic or subject.

Portuguese uses definite articles much more often than English.

Here, the article shows that these are specific things already known in context:

• o rascunho = the draft
• o tema = the topic
• o resumo = the summary

Even where English might sometimes say:

• After rereading draft... (less natural but possible in note-like style) Portuguese normally wants:
• Depois de reler o rascunho...

Using the article is the standard choice here.

Because bom is an adjective, and it describes o tema.

• bom = good
• bem = well

So:

• o tema estava bom = the topic was good
• not o tema estava bem in this meaning

Estar bem usually means to be well / to be okay, often about health or condition:

• Estou bem. = I’m fine.

But here the speaker is evaluating the quality of the topic, so bom is correct.

Here, demais means too or excessively.

So:

• longo demais = too long

This is a very common structure in Portuguese:

• caro demais = too expensive
• difícil demais = too difficult
• tarde demais = too late

A useful contrast:

• muito longo = very long
• longo demais = too long

So demais expresses excess, not just intensity.

That is simply the normal Portuguese word order for this expression.

Portuguese says:

• longo demais
• literally something like long too-much

English says:

• too long

So although the meaning matches English too, the position is different. This is something learners just need to get used to.

It is very natural and usually recommended.

• Depois de reler o rascunho, percebi...

The comma separates the introductory phrase from the main clause. In writing, this makes the sentence easier to read.

You may sometimes see short introductory phrases without a comma, but in a sentence like this one, the comma is standard and stylistically better.

Usually, keeping it is the most natural choice:

• o tema estava bom, mas o resumo estava longo demais

In English, we often omit repeated verbs more freely:

• the topic was good, but the summary too long
  That kind of omission is less natural in standard Portuguese here.

Repeating estava makes the contrast clear and sounds complete and idiomatic.

Yes, by default, that is how it is understood.

The sentence naturally means:

• After rereading the draft, I realized...

So the person who reread is also the person who realized.

If the subject were different, Portuguese would usually make that clearer, for example with a different structure or an explicit subject. As written, the most natural interpretation is that both actions belong to the same person.