Learn Hardcore Indonesian: Dari langit-langit, debu jatuh sedikit; tukang akan bersih-bersih sesudah selesai. - From the ceiling, a little dust falls; the worker will clean up after finishing.

Because langit means “sky,” while the reduplicated form langit-langit is a fixed word meaning “ceiling.” This is lexicalized reduplication. You’ll also see the loanword plafon used for “ceiling.” In standard spelling, reduplication is written with a hyphen: langit-langit.

Is dari the right preposition here? Could I use di instead?

dari = “from,” marking the source/origin: Debu jatuh dari langit-langit (Dust falls from the ceiling).
di = “at/on/in,” marking location: Ada debu di langit-langit (There is dust on the ceiling).

Don’t use daripada here; that’s for comparisons (e.g., “than”).

Is fronting the phrase Dari langit-langit natural, or should it go at the end?

Fronting to set the scene or topic is fine and common in Indonesian. You could also put the source at the end:

Debu jatuh sedikit dari langit-langit. Both orders are acceptable; choose the one that highlights what you want to talk about first.

What exactly does sedikit modify here? Is there a difference between Debu jatuh sedikit and Sedikit debu jatuh?

Yes:

Debu jatuh sedikit: sedikit modifies the verb “fall” (it fell a bit/to a small extent).
Sedikit debu jatuh: sedikit quantifies the noun (a small amount of dust fell).

A very natural way to say “some dust fell” is: Ada sedikit debu yang jatuh (dari langit-langit).

Would berjatuhan be better than jatuh when talking about dust?

Berjatuhan suggests many small items falling here and there or continuously. It often sounds more natural for particles:

Debu berjatuhan dari langit-langit. Use jatuh for a simple “fall” event; use berjatuhan to emphasize scattered/ongoing falling.

How can I make “the dust” or “a bit of dust” explicit?

“the dust”: debunya or debu itu.
“a bit of dust”: sedikit debu or ada sedikit debu. Examples:
Debunya jatuh dari langit-langit.
Ada sedikit debu jatuh dari langit-langit.

What does tukang mean exactly? Is it polite?

Tukang is a general word for a tradesperson/handyman (manual worker), e.g., tukang kayu (carpenter), tukang cat (painter), tukang ledeng (plumber). It’s neutral for such roles. For “worker” in general, pekerja is common; for a contractor, kontraktor. Use tukang itu or tukangnya for “the worker (in question).”

How do I show singular vs plural for tukang?

Indonesian often leaves number unmarked; tukang can mean “worker” or “workers.” To be explicit:

Singular: seorang tukang
Plural: para tukang (more formal) or tukang-tukang
Definite: tukang itu / tukangnya

Why use bersih-bersih instead of membersihkan?

bersih-bersih (reduplication) = to do cleaning in general (intransitive, no required object): Tukang akan bersih-bersih.
membersihkan (transitive) = to clean something (needs an object): Tukang akan membersihkan lantai. Use bersih-bersih when you don’t want to specify an object or mean “do some cleaning.”

Could I say beres-beres instead of bersih-bersih?

You could, but the nuance differs:

bersih-bersih focuses on cleaning (removing dirt).
beres-beres focuses on tidying/putting things in order. Often both happen together, but they’re not identical.

Is akan required to talk about the future?

No. Indonesian doesn’t require a future marker. Options:

Omit it: Tukang bersih-bersih sesudah selesai.
Use akan (neutral/standard future): Tukang akan bersih-bersih...
Use nanti (“later”): Nanti tukang bersih-bersih...
Colloquial: bakal or intent mau: Tukang bakal/mau bersih-bersih... You can combine time words: Nanti tukang akan bersih-bersih.

Is sesudah selesai redundant? What does it literally mean?

It’s fine and idiomatic. sesudah (“after”) + selesai (“finished/complete”) gives “after (it’s) finished.” The subject/object is understood from context. You can make it explicit:

sesudah dia selesai (bekerja)
sesudah pekerjaannya selesai Synonyms: setelah selesai, begitu selesai (“as soon as it’s finished”).

Are setelah and sesudah interchangeable? What about habis or usai?

setelah and sesudah are near-synonyms; setelah is extremely common.
habis (itu) is colloquial (“after/after that”).
usai/seusai is more formal/literary. All can work; pick based on register and style.

Could I use the passive, like akan dibersihkan?

Yes. Passive is natural when the object is the focus:

Area ini akan dibersihkan sesudah (pekerjaan) selesai.
Rumahnya akan dibersihkan setelah selesai. Active vs passive is a matter of focus and style.

Is the comma after Dari langit-langit and the semicolon before tukang normal in Indonesian?

It’s acceptable, but many writers would simply use two sentences or a comma with a connector:

Dari langit-langit, debu jatuh sedikit. Tukang akan bersih-bersih sesudah selesai.
..., lalu/kemudian tukang akan bersih-bersih... Semicolons are less common in everyday Indonesian.

Can I say plafon instead of langit-langit?

Yes. Plafon is very common in everyday speech. For example:

Dari plafon, debu berjatuhan... Both plafon and langit-langit mean “ceiling.”

Can I use sesudahnya at the end, as in Tukang akan bersih-bersih sesudahnya?

Sesudahnya means “afterwards/after that.” It refers to a previously mentioned event, so it’s fine if the context is clear:

If the prior activity is obvious: Tukang akan bersih-bersih sesudahnya.
If not, prefer an explicit phrase: Tukang akan bersih-bersih sesudah (pekerjaan) selesai.