Learn Hardcore Indonesian: Kami bingung dengan pilihan tempat duduk karena kereta penuh. - We are confused by the seat choices because the train is full.

kami excludes the listener (we = me + my group, not you).
kita includes the listener (we = you and I). Here, the speaker is talking about their group’s experience, not including the listener, so kami fits.

Is bingung a verb or an adjective? Do I need a word for “to be”?

Bingung is a stative adjective meaning “confused,” and Indonesian doesn’t require a “to be” verb with adjectives. So Kami bingung literally means “We confused” → “We are/were confused.” You can add emphasis with sangat/sekali/banget: Kami sangat bingung.

Why use dengan after bingung? Could I use tentang/soal/akan/terhadap instead?

bingung dengan X is very common: “confused about/by X.”
bingung soal/tentang X also works (soal is more casual, tentang neutral).
bingung akan X is more formal/literary.
bingung terhadap X is rare/nonnative in this context. Most natural: bingung dengan or bingung soal/tentang.

Would it be more natural to say Kami bingung mau duduk di mana?

Very natural. Kami bingung mau duduk di mana karena kereta penuh = “We were confused about where to sit because the train was full.” Using mau + [question word] is often smoother than a noun like pilihan.

What exactly does pilihan tempat duduk mean? Is it “seat options” or “seat selection”?

It can mean both depending on context:

“seat options/choices” (the available seats),
or “seat selection” (the act/feature of choosing seats). Grammatically, pilihan (choice/selection) + tempat duduk (seat) is a noun–noun compound: “choices concerning seats.” You can specify availability: pilihan tempat duduk yang tersedia.

Why is there no yang between pilihan and tempat duduk?

Yang introduces a relative clause. Here we have a straightforward noun compound (pilihan + tempat duduk), so yang isn’t needed. You’d use yang if you add a clause: pilihan tempat duduk yang tersedia/yang kami lihat.

Can I use kursi instead of tempat duduk?

tempat duduk = seat (a place to sit; often used for seats on transport, theaters, etc.).
kursi = chair (the physical object). On a train, tempat duduk is the usual term for a seat; kursi is also understandable but less precise in ticketing/assignment contexts. Bangku = bench.

How do I show definiteness like “the seat choices”?

Indonesian has no articles. Use determiners or modifiers:

pilihan tempat duduk itu (those/the seat choices we’ve been talking about),
pilihan tempat duduk yang tersedia (the available seat choices),
pilihan tempat duduknya (the seat choices in question; context-bound “the”).

Can I move the karena clause to the front?

Yes. Karena kereta penuh, kami bingung dengan pilihan tempat duduk. Both orders are natural. If fronted, a comma is customary in writing.

Should I use jadi instead of karena? Can I say both: karena … jadi …?

karena = because (introduces cause).
jadi = so/therefore (introduces result). You can say either:
Cause → result: Kereta penuh, jadi kami bingung…
Result because cause: Kami bingung… karena kereta penuh. Standard Indonesian avoids double marking (karena … jadi …) in formal writing, though it’s common in casual speech.

Why is there no “to be” in kereta penuh? Should it be kereta itu penuh or keretanya penuh?

Adjectives can function as predicates: kereta penuh = “the train is full.” To make it definite:

kereta itu penuh (“that/the train is full”).
keretanya penuh (“the train is full,” with context-bound definiteness or emphasis).

Is kereta the same as kereta api? And in Malaysia kereta means “car,” right?

In Indonesian:

kereta or kereta api = train (both fine).
mobil = car. In Malaysian Malay:
kereta = car,
kereta api = train. So context and country matter.

How do I indicate past time (“was full”)?

Use time words or aspect markers:

tadi (earlier), kemarin (yesterday), waktu itu (at that time),
sudah (already), baru saja/barusan (just). Example: Kami tadi bingung… karena kereta sudah penuh.

Does penuh mean “crowded”? How is it different from ramai, padat, sesak?

penuh = full (at capacity).
sesak = cramped/stuffy/overcrowded (uncomfortably packed).
padat = dense/heavily packed (often neutral-formal).
ramai = busy/lively/crowded (not necessarily over capacity). You can intensify: penuh sekali / penuh banget / penuh sesak.