Learn Hardcore Indonesian: Kami kekurangan staf di kantor malam ini. - We are short of staff at the office tonight.

The base word is kurang (less/insufficient).
The circumfix ke- -an turns it into a state/result: kekurangan = to be short of, to lack; also “a shortage” (noun).
In this sentence it functions as a stative verb: “to be lacking (in) staff.”
As a noun you’d say: Ada kekurangan staf di kantor (There is a staff shortage at the office).

Can I say kami kurang staf instead of kami kekurangan staf? What’s the nuance?

Yes. Both are common and natural.

kekurangan staf: slightly more formal or structural-sounding; emphasizes an objective shortage.
kurang staf: very common in everyday speech; emphasizes “not enough staff (right now/for this need).” You can add aspect:
sedang (standard) or lagi (colloquial) for “currently”: Kami sedang/lagi kekurangan staf.

Why use kami and not kita?

kami = we (excluding the listener).
kita = we (including the listener).
Use kami if you’re speaking to someone outside your team/office. Use kita if you’re speaking to fellow coworkers affected by the shortage: Kita kekurangan staf…

Is staf singular or plural? How do I specify number?

Indonesian doesn’t mark plural by default, and staf behaves like a mass/collective noun.

To count people: seorang staf (one staff member), dua orang staf, beberapa staf, sejumlah staf, para staf (the staff, collectively).
You’ll also see dua staf in the wild; it’s widely used, though many prefer inserting orang to emphasize people.
Avoid reduplication (staf-staf) for plurality; it sounds odd here.

Are there better words than staf in different contexts?

Common options (pick by context/register):

pegawai: employees (often public sector, but general too)
karyawan: employees (commonly private sector)
personel: personnel (more formal/official)
petugas: on-duty staff/attendants/officers
tenaga (kerja): manpower
kru: crew (e.g., hotel/airline/event)
All can fit the pattern: kekurangan karyawan/personel/tenaga/kru.

Is the word order with di kantor malam ini correct? Can I move malam ini?

Yes, it’s natural to place time at the end. Variations:

Malam ini, kami kekurangan staf di kantor. (fronted time)
Kami kekurangan staf di kantor malam ini. (your version)
Di kantor malam ini, kami kekurangan staf. (fronted place+time; add a comma in writing)
Indonesian allows flexible placement for time/place adverbs to adjust emphasis.

Should I say di malam ini for “tonight”?

No. Use malam ini (neutral) or pada malam ini (formal).
di malam ini is generally ungrammatical in standard prose (though di malam hari = “at night” is fine for general time).

What’s the difference between malam ini and nanti malam?

malam ini = tonight (this evening/night).
nanti malam = later tonight (future-leaning; useful earlier in the day).
If it’s already evening, malam ini fits best; nanti malam can still work if you mean “later on tonight.”

Does the sentence mean “we are short-staffed now” or “we will be tonight”? Indonesian has no tense—how do I show time clearly?

The time adverb does the work:

… malam ini alone can point to tonight (often future relative to now).
Add akan to stress future: Kami akan kekurangan staf malam ini.
Add sedang/lagi for “currently (ongoing)”: Kami sedang/lagi kekurangan staf (sekarang).

Does di kantor mean the physical office? What if I want to be explicit it’s our office?

di kantor usually means “at the office” (the location), understood from context. To be explicit, say di kantor kami. You can also rephrase:

Kantor kami kekurangan staf malam ini. (makes “our office” the topic)

Could di kantor attach to staf, like “office staff,” and would that change the meaning?

Yes, attachment changes meaning:

Kami kekurangan staf di kantor… = we are short of staff at the office (place adverbial).
Kami kekurangan staf kantor… = we are short of office staff (type of staff, contrasted with, say, field staff).
Use the version that matches your intended focus (place vs. type).

How do I negate or ask a question with this pattern?

Negation: Kami tidak kekurangan staf di kantor malam ini.
Yes/no question (formal): Apakah kami/kita kekurangan staf di kantor malam ini?
Colloquial: Kita kekurangan staf malam ini? (rising intonation)
Wh-question: Kenapa kita kekurangan staf malam ini? (Why are we short-staffed tonight?)