Din moment ce dosarul este incomplet, solicitantul așteaptă.

Here din moment ce means since / given that / seeing that.

In this sentence:

• Din moment ce dosarul este incomplet, solicitantul așteaptă.
• Since the file/application is incomplete, the applicant waits.

It can often be translated as because, but the tone is slightly different:

• pentru că = the most direct everyday because
• fiindcă = also because
• din moment ce = since / given that, often presenting the reason as an already accepted fact

So din moment ce sounds a little more like: given that the file is incomplete...

The comma separates the reason clause from the main clause.

• Din moment ce dosarul este incomplet = subordinate clause giving the reason
• solicitantul așteaptă = main clause

Romanian normally uses a comma when a subordinate clause comes first, just like English often does:

• Since the file is incomplete, the applicant waits.

So the comma is very natural and expected here.

Dosarul means the file / the dossier / the application file.

Romanian often adds the definite article to the end of the noun instead of putting a separate word like the in front.

• dosar = a file
• dosarul = the file

This is called the enclitic definite article.

For masculine/neuter singular nouns, the definite article is often -ul:

• băiat → băiatul = the boy
• dosar → dosarul = the file

So dosarul este incomplet literally means the file is incomplete.

For the same reason as dosarul:

• solicitant = an applicant
• solicitantul = the applicant

Romanian marks definiteness at the end of the noun:

• solicitantul așteaptă = the applicant waits

So both nouns in the sentence are definite:

• dosarul = the file
• solicitantul = the applicant

Yes. Este is the full form of is, from the verb a fi (to be).

• dosarul este incomplet = the file is incomplete

In everyday speech, Romanians very often use e instead of este:

• dosarul e incomplet

Both are correct. In general:

• este = slightly more formal, fuller
• e = very common in speech and informal writing

So the sentence could also be:

• Din moment ce dosarul e incomplet, solicitantul așteaptă.

It does agree with dosarul.

The noun dosar is a neuter noun. In Romanian, neuter nouns behave:

• like masculine in the singular
• like feminine in the plural

Since dosarul is singular, the adjective takes the singular masculine-looking form:

• dosarul este incomplet = singular

Compare:

• dosarul incomplet = the incomplete file
• dosarele incomplete = the incomplete files

So incomplet is the correct agreeing form here.

Așteaptă is present tense, 3rd person singular, from the verb a aștepta (to wait).

Here are a few forms:

• eu aștept = I wait / am waiting
• tu aștepți = you wait
• el/ea așteaptă = he/she waits
• solicitantul așteaptă = the applicant waits

Romanian present tense can often correspond to both English:

• waits
• is waiting

depending on context.

So solicitantul așteaptă could mean either:

• the applicant waits
• the applicant is waiting

No, it does not have to include an object.

A aștepta can be used:

• with an object: așteaptă un răspuns = he/she is waiting for an answer
• without an object: așteaptă = he/she waits / is waiting

In your sentence, the object is simply not stated. The focus is on the situation:

• because the file is incomplete, the applicant waits

In real context, the person may be waiting for processing, for missing documents, for approval, etc., but Romanian does not need to specify that here.

Yes, it could be reversed.

The current version starts with the reason:

• Din moment ce dosarul este incomplet, solicitantul așteaptă.
• Since the file is incomplete, the applicant waits.

You can also put the main clause first:

• Solicitantul așteaptă, din moment ce dosarul este incomplet.

That is grammatically possible, but the original order is more natural if you want to foreground the reason first.

Romanian word order is fairly flexible, but different orders can change emphasis.

Not always perfectly.

They are often close in meaning, but they are not identical in tone:

• pentru că = straightforward because
• din moment ce = since / given that / seeing that

Compare:

• Solicitantul așteaptă pentru că dosarul este incomplet.
  = The applicant waits because the file is incomplete.

• Din moment ce dosarul este incomplet, solicitantul așteaptă.
  = Since the file is incomplete, the applicant waits.

The second version can sound a bit more logical or explanatory, as if the reason is already established.

A rough pronunciation is:

• dosarul ≈ doh-SAH-rul
• solicitantul ≈ soh-lee-chee-TAN-tool
• așteaptă ≈ uhsh-TEAP-tuh

A few helpful points:

• Romanian ă is a short central vowel, something like the vowel in sofa.
• The ending -ul in words like dosarul is pronounced, but in normal speech it can sound light and quick.
• ș is pronounced sh.
• ț would be pronounced ts (not used in this sentence).
• ce is pronounced roughly like che in check, but softer: che / tʃe.

So:

• Din moment ce ≈ deen moh-MENT che
• dosarul este incomplet ≈ doh-SAH-rul YES-teh een-kohm-PLET

Dosar usually means file, dossier, or case file.

Depending on context, it can refer to:

• a physical folder of documents
• an administrative application file
• a legal case file
• a set of papers in an official process

So in this sentence, dosarul este incomplet most likely means:

• the application file is incomplete
• the case file is incomplete
• the document file is incomplete

The exact English translation depends on context.

Yes. Even though din moment ce is often best translated as since / given that, the overall meaning is absolutely causal.

So the sentence naturally conveys:

• The applicant is waiting because the file is incomplete.

The nuance is just that Romanian presents the incompleteness as an established fact from which the result follows.

So both of these English renderings are possible:

• Since the file is incomplete, the applicant is waiting.
• Because the file is incomplete, the applicant is waiting.

It is normal and correct, but it has a somewhat formal or administrative feel because of the vocabulary:

• dosarul = the file / dossier
• solicitantul = the applicant

This sounds like language from:

• official notices
• administrative procedures
• legal or bureaucratic contexts

In casual speech, someone might use less formal wording depending on the situation. But as an official-style sentence, it sounds very natural.