Pričuva me ne brine toliko koliko stara brava na ulaznim vratima.

In everyday Croatian, pričuva often means the building reserve fund or maintenance fee for an apartment building. It is money residents pay for shared repairs and upkeep.

So here, pričuva is not a general idea like reserve in English, but a very specific housing-related expense.

Because brinuti can work in two different ways:

• brinem = I worry
• brine me = it worries me / it concerns me

In this sentence, the subject is pričuva, so the structure is:

• Pričuva me brine = The reserve fund worries me
• literally: The reserve fund concerns me

So me is the object form meaning me, while brine is it worries.

Croatian often places short pronouns like me, te, ga, je, se in the second position of the clause. These are called clitics.

So:

• Pričuva me ne brine...

sounds natural because me comes very early, right after the first stressed word.

You should not think of Croatian word order as identical to English word order. The placement of these little words follows Croatian rhythm and grammar rules, not English-style logic.

Because the subject pričuva is singular.

• pričuva = singular
• brine = worries / concerns

If the subject were plural, then you would use brinu:

• Troškovi me brinu. = The costs worry me.

Here, though, there are two things being compared, but the main subject before the verb is still just pričuva.

This is a very common comparison pattern in Croatian:

• ne ... toliko koliko ...

It means:

• not as much as
• not so much as

So:

• Pričuva me ne brine toliko koliko stara brava...
• The reserve fund does not worry me as much as the old lock...

This is a comparison of degree: one thing worries the speaker less than another thing.

Yes, koliko often means how much / how many, but in comparisons it can also mean as in the sense of as much as.

So in this structure:

• toliko koliko

it works like:

• as much as
• to the extent that

Examples:

• Ne košta toliko koliko sam mislio. = It doesn’t cost as much as I thought.
• Ne volim ga toliko koliko ona. = I don’t like him as much as she does.

So in your sentence, koliko is part of a comparison, not a question word.

Because it is understood as the subject of the second half of the comparison.

The full underlying structure is roughly:

• Pričuva me ne brine toliko koliko me brine stara brava na ulaznim vratima.

The repeated me brine is omitted because Croatian often leaves out words that are obvious from context.

So stara brava stays in the nominative because it is the thing that worries the speaker.

Because na can take different cases depending on meaning:

• na + accusative = movement onto/toward
• na + locative = location on/at

Here the meaning is location:

• on the entrance door
• at the entrance door

So Croatian uses the locative:

• na ulaznim vratima

If there were movement, you would expect accusative instead.

In Croatian, vrata is a plural-only noun in standard usage for door/doors. This is very normal and one of those things you simply learn as vocabulary.

So:

• nominative: vrata
• locative/instrumental/dative plural: vratima

Even when English says the door, Croatian usually says vrata.

That is why you get:

• na vratima = on the door / at the door

not a singular form.

It is locative plural.

Breakdown:

• na
  • location → locative
• vrata is plural → vratima
• adjective must agree with the noun → ulaznim

So:

• na ulaznim vratima = on the entrance door

Both the adjective and noun are plural locative.

Ulazni means entrance, entry, or front depending on context.

So:

• ulazna vrata = entrance door, front door, main entry door

In this sentence, it refers to the main door at the entrance, not just any interior door.

Yes, Croatian word order is flexible, but some versions sound more natural than others.

The original:

• Pričuva me ne brine toliko koliko stara brava na ulaznim vratima.

is natural and clear.

You could also say:

• Ne brine me toliko pričuva koliko stara brava na ulaznim vratima.

This is also natural and puts slightly more focus on the comparison.

What you usually want to preserve is:

• the clitic placement of me
• the comparison pattern ne ... toliko koliko ...

Yes. Croatian often omits repeated material when it is obvious.

The full version would be:

• Pričuva me ne brine toliko koliko me brine stara brava na ulaznim vratima.

But repeating me brine would sound heavier and less elegant, so it is normally left out.

This kind of omission is very common in Croatian comparisons.

A fairly literal breakdown would be:

• Pričuva = the reserve fund / maintenance fee
• me = me
• ne brine = does not worry / concern
• toliko koliko = as much as
• stara brava = the old lock
• na ulaznim vratima = on the entrance door

So the literal structure is:

• The reserve fund does not worry me as much as the old lock on the entrance door.

That is very close to natural English, which is why this sentence is a nice example of how Croatian comparison can line up quite well with English.