ההבטחה הזאת עדיין לא מספיקה לי, ולכן אין לי אמון מלא בו.

In Hebrew, demonstratives like הזה / הזאת / האלה usually come after the noun:

• ההבטחה הזאת = this promise
• הספר הזה = this book
• הילדה הזאת = this girl

Also, both parts are definite:

• ההבטחה = the promise
• הזאת = this

So Hebrew literally says something like the promise this, even though in natural English we say this promise.

That is normal in Hebrew. When a noun is followed by this/that, the noun itself is still marked as definite with ה־.

So:

• הבטחה = a promise
• ההבטחה הזאת = this promise

You do not usually say הבטחה הזאת in standard Hebrew. The noun and the demonstrative go together as a definite phrase.

Because הבטחה is a feminine singular noun, and the adjective/verb form has to agree with it.

• הבטחה = feminine singular
• therefore: מספיקה

Compare:

• הספר מספיק לי = The book is enough for me
• ההבטחה מספיקה לי = The promise is enough for me

In this sentence, מספיקה means is enough / suffices.

מספיקה לי means is enough for me or suffices for me.

Breakdown:

• מספיקה = is enough / suffices
• לי = to me / for me

Hebrew often uses ל־ where English uses for in this kind of expression.

So:

• זה מספיק לי = This is enough for me
• ההבטחה הזאת לא מספיקה לי = This promise is not enough for me

עדיין means still.

In this sentence:

• ההבטחה הזאת עדיין לא מספיקה לי
• This promise is still not enough for me

It often appears before לא when you mean still not:

• אני עדיין לא יודע = I still don’t know
• היא עדיין לא הגיעה = She still hasn’t arrived

So עדיין לא is a very common combination.

ולכן means and therefore, and so, or therefore.

Breakdown:

• ו־ = and
• לכן = therefore / thus

It connects the two parts logically:

• This promise is still not enough for me
• therefore I do not have full trust in him/it

It is a bit more formal or structured than simply using אז (so), but it is very common in both spoken and written Hebrew.

Hebrew expresses possession with יש (there is / there are / have) and אין (there is not / do not have), not with a verb like English to have.

So:

• יש לי אמון = I have trust
• אין לי אמון = I do not have trust

Literally, אין לי אמון is something like There is no trust to me, but in natural English it means I don’t have trust.

Using אני לא יש... is not grammatical.

אמון means trust, confidence, or faith depending on context.

In this sentence, אין לי אמון מלא בו means I do not have full trust in him/it.

A useful distinction:

• אמון ב־ = trust in
• לבטוח ב־ = to trust

So you could also say:

• אני לא בוטח בו לגמרי = I don’t fully trust him

But the original sentence uses the noun אמון rather than the verb.

In Hebrew, adjectives usually come after the noun.

So:

• אמון מלא = full trust
• בית גדול = a big house
• אישה חכמה = a smart woman

That is the normal word order.

Sometimes Hebrew can place something before the noun for stylistic reasons, but in ordinary usage noun + adjective is the standard pattern.

בו means in him / in it.

It is made of:

• ב־ = in / at / on, but with some verbs and nouns it corresponds to English in
• הוא = he
• together: בו = in him / in it

With אמון, Hebrew says אמון ב־ מישהו/משהו:

• יש לי אמון בו = I have trust in him/it
• אין לי אמון בה = I don’t have trust in her/it

Even though English says trust him or trust in him depending on style, Hebrew normally uses ב־ with אמון.

It can refer to either, depending on context.

• If the earlier context is about a man, בו = in him
• If it refers to a masculine noun, it can also mean in it

So the sentence could mean:

• I do not fully trust him or
• I do not have full trust in it

The grammar alone does not tell you which one is intended; the context does.

Yes, the word order is natural and standard.

The sentence is:

• ההבטחה הזאת עדיין לא מספיקה לי, ולכן אין לי אמון מלא בו.

You could rearrange parts for emphasis, but the original is very natural.

For example, you might also hear:

• עדיין אין לי אמון מלא בו, כי ההבטחה הזאת לא מספיקה לי.

That changes the focus a bit, but the original version is clear and idiomatic.

It sounds mostly neutral to slightly formal.

Reasons:

• ולכן is a bit more formal than very conversational אז
• אמון מלא sounds thoughtful and natural, but slightly more formal than a simpler phrase like אני לא ממש סומך עליו

A more conversational version might be:

• ההבטחה הזאת עדיין לא מספיקה לי, אז אני לא ממש סומך עליו.

That means roughly the same thing, but sounds more spoken.