Adik saya kadang bawel kalau lapar, tetapi komentarnya tentang harga tiket tadi benar-benar masuk akal.

Adik means younger sibling. By itself, it does not tell you whether the person is male or female.

So adik saya can mean:

• my younger brother
• my younger sister
• more generally, my younger sibling

If Indonesian wants to be specific, it can add:

• adik laki-laki = younger brother
• adik perempuan = younger sister

Both are possible, but they work a little differently.

• adik saya = my younger sibling
• saya punya adik = I have a younger sibling

In your sentence, the speaker is identifying the person, so adik saya is the natural choice.

Indonesian often shows possession by simply putting the possessor after the noun:

• rumah saya = my house
• teman saya = my friend
• adik saya = my younger sibling

Kadang means sometimes.
Kadang-kadang also means sometimes.

In everyday Indonesian, both are common. Kadang-kadang can sound a little fuller or slightly more emphatic, but in many contexts they are interchangeable.

Examples:

• Saya kadang lupa. = I sometimes forget.
• Saya kadang-kadang lupa. = I sometimes forget.

Bawel is a very common informal word. It can mean things like:

• fussy
• complaining a lot
• nagging
• talkative in an annoying way

In this sentence, kadang bawel kalau lapar suggests that the younger sibling gets whiny / grumpy / complains a lot when hungry.

It is not usually a very harsh insult, but it is definitely not a formal word.

Because the subject is already clear from context.

In Adik saya kadang bawel kalau lapar, the understood subject of lapar is the same as adik saya. Indonesian often omits pronouns when they are obvious.

So:

• Adik saya kadang bawel kalau lapar
  literally feels like
• My younger sibling is sometimes fussy when hungry

You could say kalau dia lapar, but it is not necessary here.

It can mean both, depending on context.

Here, kalau lapar is best understood as when hungry or whenever hungry, not as a one-time uncertain condition.

So this part means something like:

• sometimes gets fussy when hungry
• can be fussy if hungry

In casual Indonesian, kalau is extremely common for both if and when.

Yes. They mean the same thing: but.

• tetapi = a bit more formal or careful
• tapi = more conversational and common in speech

So the sentence could also be:

• Adik saya kadang bawel kalau lapar, tapi komentarnya ...

Both are natural. Tetapi just sounds slightly more polished.

Komentarnya comes from komentar + -nya.

The ending -nya can do several things in Indonesian. Here it most naturally means his/her/their or sometimes the depending on context.

So komentarnya here most likely means:

• his/her comment
• his/her remarks
• the comment

Since the sentence has already mentioned adik saya, -nya is understood as referring back to that person.

Compare:

• komentar adik saya = my younger sibling’s comment
• komentarnya = his/her comment

Yes. Tentang means about / concerning.

So:

• komentarnya tentang harga tiket = his/her comment about ticket prices

Also note harga tiket:

• harga = price
• tiket = ticket

In Indonesian, nouns often combine directly like this:

• harga tiket = ticket price / ticket prices
• harga makanan = food price / food prices

The language usually does not mark singular vs. plural unless needed by context.

Tadi usually refers to something earlier, often earlier today or just now.

In this sentence, it modifies the situation being talked about:

• tentang harga tiket tadi = about the ticket price(s) earlier / from earlier

So the speaker is referring to a recent earlier moment in the conversation or situation.

Useful comparison:

• tadi = earlier / a little while ago
• kemarin = yesterday
• dulu = before / in the past / long ago

Masuk akal is a fixed expression meaning:

• makes sense
• is reasonable
• is logical

Benar-benar means really / truly / genuinely.

So:

• benar-benar masuk akal = really makes sense / is genuinely reasonable

Literally, masuk akal looks like enter reason, but you should learn it as a set phrase meaning to be sensible.

Because Indonesian often does not need a copula like is, are, was, or were.

So:

• Komentarnya ... masuk akal
  literally looks like
• His/her comment ... sensible

But in natural English, we translate it as:

• His/her comment ... was really reasonable
• His/her comment ... really made sense

This is very normal in Indonesian:

• Dia marah. = He/She is angry.
• Rumah itu besar. = That house is big.
• Komentarnya masuk akal. = The comment makes sense / is reasonable.

Yes, it sounds natural.

It has a mostly neutral everyday feel, with a slight mix of casual and formal elements:

• bawel is informal and conversational
• tetapi is a bit more formal than tapi
• benar-benar masuk akal is neutral and very natural

So overall, it sounds like normal Indonesian, especially in writing or careful speech. In very casual conversation, many speakers might say:

• Adik saya kadang bawel kalau lapar, tapi komentarnya tentang harga tiket tadi bener-bener masuk akal.

Here bener-bener is the colloquial spoken form of benar-benar.