Learn Hardcore Indonesian: Pembaruan aplikasi membuat akun kami sinkron lagi. - The application update makes our accounts in sync again.

Indonesian puts the head noun first, followed by its modifier. pembaruan aplikasi literally means “update (of) application,” i.e., “an app update.” If you reverse it to aplikasi pembaruan, it would mean “an application for updates,” which is different. You can also say:

pembaruan pada aplikasi (more explicit: “an update on the app”)
pembaruan aplikasi itu/ini to specify “that/this app update”

Is pembaruan the right word for “update”? How does it differ from pembaharuan, memperbarui, or the loanword update?

pembaruan = the noun “an update.”
memperbarui / perbarui = the verb “to update.”
pembaharuan is an older/less preferred variant; modern Indonesian favors forms from baru: pembaruan, memperbarui.
The loan update is very common in speech/informal writing (di-update, meng-update, nge-update). In formal contexts, prefer diperbarui/memperbarui or pembaruan.

Why use membuat here? Could I say menjadikan or add menjadi?

membuat + noun phrase + adjective is a common causative pattern: “make X [adjective].” So membuat akun kami sinkron = “make our accounts in sync.” Alternatives:

menjadikan is slightly more formal: Pembaruan aplikasi menjadikan akun kami sinkron lagi.
Adding menjadi is optional but heavier: membuat akun kami menjadi sinkron lagi. Avoid membuatkan here; that means “make for (someone).”

Can I use a verb meaning “to synchronize” instead of membuat … sinkron?

Yes. Use menyinkronkan (meN- + sinkron + -kan):

Pembaruan aplikasi menyinkronkan akun kami lagi. This is concise and common. Note:
Standard spelling is menyinkronkan (not the nonstandard but common mensinkronkan).
The related noun is sinkronisasi: pembaruan itu melakukan sinkronisasi akun (more formal).

What does lagi do here, and where can it go? How is it different from kembali or sekali lagi?

lagi after a verb/adjective often means “again”: sinkron lagi = “in sync again.” Placing it at the end is natural.
kembali can replace lagi and sounds a bit more formal or “back to a previous state”: akun kami kembali sinkron.
sekali lagi = “one more time” and usually modifies an action, not a state, so it doesn’t fit this sentence. Tip: With adjectives, kembali typically goes before (kembali sinkron), while lagi usually comes after (sinkron lagi).

Why kami and not kita?

kami = we/us, excluding the listener.
kita = we/us, including the listener. Use kami if you’re speaking to someone outside the group whose accounts were synced. Use kita if you include the person you’re talking to.

Does akun kami mean one account or multiple accounts?

Indonesian doesn’t require plural marking, so akun kami can mean “our account” or “our accounts.” To emphasize plural, you can use:

akun-akun kami
a quantifier: dua akun kami, banyak akun kami, sejumlah akun kami Don’t use para; that’s only for people.

Do I need to say what the accounts are in sync with, like “with the server”?

Only if it’s not obvious. To specify, add dengan:

… sinkron lagi dengan server.
… sinkron dengan satu sama lain. Using the verb is also fine: menyinkronkan akun kami dengan server.

There’s no past tense marking. How do I show this already happened?

Use aspect markers or time words:

Completed: sudah / telah — Pembaruan aplikasi sudah/telah membuat akun kami sinkron lagi.
Future: akan — … akan membuat …
Time adverbs: kemarin (yesterday), barusan (just now), tadi (earlier)

Is the sentence formal or casual? What are natural alternatives?

Neutral. Alternatives:

More formal: Pembaruan aplikasi telah menjadikan akun kami kembali sinkron.
Casual/spoken: Setelah update, akun kami sinkron lagi. or Aplikasi yang di-update bikin akun kami sinkron lagi.

Any common spelling or word-choice pitfalls?

Prefer pembaruan (modern) over pembaharuan (older).
Verb: memperbarui (not memperbaharui) for “to update.”
sinkron uses k, and the verb is menyinkronkan.
Loan forms like di-update are informal.

Why no yang before sinkron? Could I say … akun kami yang sinkron lagi?

In the causative membuat + noun phrase + adjective, you don’t use yang. yang introduces a relative clause or marks an adjective that modifies a noun. akun kami yang sinkron lagi means “our accounts that are (now) in sync,” not “make our accounts in sync.” Keep it as membuat akun kami sinkron lagi.

Is sinkron an adjective or a verb here?

It’s an adjective meaning “in sync.” Indonesian allows adjectives as complements after membuat. If you want a verb, use menyinkronkan (“to synchronize”).

Is akun the right word for “account” (vs rekening)?

Yes. akun is used for app/website/service accounts. rekening is specifically a bank account. So akun is correct in tech contexts.

Can I reorder parts to emphasize cause or result?

Yes:

Cause first: Berkat pembaruan aplikasi, akun kami kembali sinkron.
Result first: Akun kami kembali sinkron berkat pembaruan aplikasi. Both are natural choices for emphasis.