Learn Hardcore Indonesian: Koordinasi yang bagus menyelamatkan rapat malam ini. - Good coordination saved tonight's meeting.

yang links a noun to a descriptor, roughly “that/which is.” So koordinasi yang bagus ≈ “coordination that is good.”
You can drop it: koordinasi bagus is also acceptable, especially in casual speech. With yang, it sounds a bit more specific/formal.
Use yang if the description is longer or behaves like a clause, e.g., koordinasi yang sangat bagus.

What’s the difference between bagus and baik here?

bagus = good/excellent in quality or performance; more casual and evaluative.
baik = good/proper/beneficial; slightly more formal or neutral.
Both work. Many would say koordinasi yang baik in formal contexts; koordinasi yang bagus is fine and common in speech.

Does malam ini modify the meeting or the whole sentence? Is it “tonight’s meeting” or “saved the meeting tonight”?

As written, rapat malam ini is often read as the noun phrase “tonight’s meeting.”
Time expressions are also commonly placed at the end, so readers may also understand it as “saved the meeting tonight.” In practice, the meaning is the same.
To make it unambiguously a time adverbial: Malam ini, koordinasi yang bagus menyelamatkan rapat.

Can I move malam ini to the front?

Yes: Malam ini, koordinasi yang bagus menyelamatkan rapat.
Fronting time expressions is very natural in Indonesian and adds topical emphasis to “tonight.”

Is menyelamatkan the right verb for salvaging a meeting?

Yes. menyelamatkan (“to save/rescue [something/someone]”) works for abstract things like meetings or situations.
Alternatives: menyelamatkan jalannya rapat (saved the conduct/proceedings of the meeting), mengamankan rapat (secured the meeting), menyelamatkan situasi (saved the situation).

How is menyelamatkan formed, and why meny-?

Root: selamat (safe).
Prefix meN-
- root + suffix -kan → menyelamatkan (“to make [something] safe; to save”).
When meN- meets an initial s, it becomes meny- and the s of the root drops: meN + selamat → meny(elamat)kan → menyelamatkan.

Can I use the passive voice?

Yes: Rapat malam ini diselamatkan (oleh) koordinasi yang bagus.
More natural alternatives: Rapat malam ini berhasil diselamatkan berkat koordinasi yang baik/bagus, or Rapat malam ini terselamatkan berkat koordinasi yang baik (journalistic style).

What’s the difference between rapat and pertemuan?

rapat: a formal/organized meeting (office, committee, board).
pertemuan: a meeting/encounter/gathering; broader and less tied to formal organizational context.
In a workplace setting, rapat is typically the right word.

Isn’t rapat also an adjective meaning “tight/close”? Any ambiguity?

Yes, rapat (adj.) can mean “tight/closed/dense,” e.g., pintu rapat (the door is tightly shut).
In this sentence, rapat is clearly a noun (object of menyelamatkan), so there’s no ambiguity.

Do I need an article like “the” or “a”? Is koordinasi countable?

Indonesian has no articles. Koordinasi here is an abstract/mass noun.
To specify: koordinasi ini/itu (this/that coordination), rapat itu (that/the meeting), rapat malam ini (tonight’s meeting).

Could I use berkat instead of making koordinasi the subject?

Yes: Berkat koordinasi yang baik/bagus, rapat malam ini terselamatkan/berhasil diselamatkan.
berkat = “thanks to/owing to” (positive nuance). karena = “because” (neutral/causal).

Is ini malam acceptable for “tonight”?

Standard Indonesian uses malam ini. ini malam is nonstandard in Indonesian (but common in Malay).

Any register tweaks to make it more formal or more casual?

More formal: Koordinasi yang baik telah/berhasil menyelamatkan rapat malam ini.
More casual: Koordinasi bagus nyelamatin rapat malam ini. (colloquial shortening of menyelamatkan → nyelamatin; not for formal writing)

Pronunciation tips?

koordinasi: ko-or-di-na-si (all vowels are clear; no diphthongs). Stress is flexible, but a light penultimate stress is common.
menyelamatkan: me-nyə-la-mat-kan (the first e is a schwa).
rapat: ra-pat. malam: ma-lam. ini: i-ni.

How can I add emphasis, like “It was good coordination that saved the meeting”?

Use -lah and a cleft-like structure: Koordinasi yang baguslah yang menyelamatkan rapat malam ini.
You can also front the cause: Justru koordinasi yang bagus yang menyelamatkan rapat malam ini.