Как бы поздно ни было, я всё равно проверяю, есть ли у кошки вода, корм и чистый лоток.

This is a very common concessive pattern in Russian:

как бы + X + ни + past-form verb

It means something like:

• no matter how X
• however X
• even if it is very X

So Как бы поздно ни было means no matter how late it is / however late it is.

This structure often expresses that the main action still happens despite some condition:

• Как бы трудно ни было, мы продолжали.
  No matter how hard it was, we continued.
• Как бы холодно ни было, он гуляет.
  No matter how cold it is, he goes for a walk.

So here it sets up the idea: regardless of how late it is, the speaker still checks on the cat.

In this pattern, бы and ни work together.

• бы helps create a kind of hypothetical/concessive meaning, similar to would / might / no matter how
• ни is part of the fixed concessive pattern and strengthens the sense of regardless of

So:

• как бы ... ни ...

is not random; it is a standard structure.

Important: this ни is not the same as ordinary sentence negation with не.
Here, ни does not simply mean not. It helps form the meaning no matter how / whatever / whoever, depending on the pattern.

Compare:

• Что бы ни случилось... = Whatever happens...
• Кто бы ни пришёл... = Whoever comes...
• Как бы поздно ни было... = However late it is...

It looks like past tense, but in this kind of construction it is not really describing past time in the normal sense.

было is the neuter singular past form of быть, but in patterns like как бы ... ни было, Russian uses this form as part of a fixed concessive/subjunctive-like structure.

So although было is formally a past-tense form, the whole phrase can refer to the present or to a general repeated situation:

• Как бы поздно ни было, я проверяю...
  = a habitual/general statement

You can think of it as similar to however late it may be.

This is normal Russian grammar, not a mistake.

Because поздно here is not an adjective describing a noun. It is a predicative adverb/state word, used in impersonal expressions about time or conditions.

Russian often says:

• Поздно. = It’s late.
• Холодно. = It’s cold.
• Темно. = It’s dark.

There is no explicit subject like it in Russian, but English usually needs one.

So:

• Как бы поздно ни было literally works like however late it may be

You would not use поздний here, because that is an adjective for nouns, as in:

• поздний вечер = a late evening
• поздний поезд = a late train

The first clause already gives the concessive idea: no matter how late it is.
But всё равно adds extra emphasis: all the same, anyway, still.

So the combination is very natural:

• Как бы поздно ни было, я всё равно проверяю...

This sounds like:

• No matter how late it is, I still check...
• However late it is, I check anyway.

Russian often likes this kind of double marking of concession:

• subordinate clause: как бы поздно ни было
• main clause emphasis: всё равно

Without всё равно, the sentence would still be correct, just a little less emphatic.

Here the present tense is being used for a habitual action:

• я проверяю = I check / I do check

It does not necessarily mean the speaker is checking right this second. It can mean this is what they regularly do.

That fits the whole sentence well:

• No matter how late it is, I still check...

Russian often uses the present tense this way for routines and general habits.

Also, проверяю is imperfective, which is the normal choice for repeated/habitual actions.

ли is used to form an indirect yes/no question.

The clause:

• есть ли у кошки вода, корм и чистый лоток

means:

• whether the cat has water, food, and a clean litter box
• literally, whether there is water, food, and a clean litter box for the cat

A key rule: ли usually comes right after the word it is questioning or focusing on.

So:

• есть ли... = whether there is / are...

Compare:

• Я не знаю, придёт ли он.
  I don’t know whether he’ll come.
• Проверь, закрыта ли дверь.
  Check whether the door is closed.

Here, the thing being questioned is the existence/availability of those items, so ли follows есть.

Because Russian usually expresses possession with у + genitive plus есть, not with a verb like to have.

So:

• у кошки есть вода
  literally: by the cat there is water idiomatically: the cat has water

This is the normal Russian way to say someone has something.

Using иметь is possible in some contexts, but it often sounds more formal, abstract, or unnatural for everyday possession. For a pet having food/water, у кошки есть... is exactly what Russian normally uses.

So:

• есть ли у кошки вода = whether the cat has water

Because after у in this possession structure, Russian uses the genitive.

Dictionary form:

• кошка = cat

After у:

• у кошки = of/at the cat, which idiomatically means the cat has

This is the standard possession pattern:

• у меня есть книга = I have a book
• у собаки есть миска = the dog has a bowl
• у кошки есть вода = the cat has water

So кошки is genitive singular because у requires it here.

Because one есть can govern all the items in the list.

So:

• есть ли у кошки вода, корм и чистый лоток

means:

• whether the cat has water, food, and a clean litter box

Russian does not need to repeat есть before each noun. English also usually would not repeat there is/are or has in a list unless you want special emphasis.

It is understood that есть applies to all three:

• water
• food
• a clean litter box

In this context:

• корм = pet food, here specifically cat food
• лоток = litter tray / litter box

A few nuances:

• корм is a broad word for feed/food for animals. In everyday pet context, it often means packaged pet food.
• чистый лоток means the litter box is clean, not just that the cat has one.

So the speaker is not just checking for objects, but for the cat’s basic needs being properly taken care of.

Because the sentence contains subordinate clauses.

1. Как бы поздно ни было is a subordinate concessive clause.
   It is separated from the main clause by a comma.

2. есть ли у кошки вода, корм и чистый лоток is another subordinate clause, this time an indirect question after проверяю.
   So it is also separated by a comma.

Structure:

• [Как бы поздно ни было], [я всё равно проверяю], [есть ли у кошки вода, корм и чистый лоток].

Russian punctuation is quite clause-based, so commas appear often where English might also use them, but sometimes more consistently.

Some parts could move around, but the given version is very natural.

For example, in the second part, you could say:

• я всё равно проверяю, есть ли у кошки...
• я всё равно проверяю, у кошки есть ли... — this is much less natural
• я проверяю, есть ли у кошки... — also fine, just less emphatic without всё равно

The given order is preferred because:

• есть ли is a very common way to begin an indirect yes/no question
• у кошки naturally comes before the list of things
• the list then follows smoothly

In the first clause, Как бы поздно ни было is also a standard and idiomatic order.

So yes, Russian word order is flexible, but this sentence already uses the most natural arrangement.

Most naturally, it describes a general habit.

That comes from several things working together:

• я проверяю is present imperfective, good for repeated actions
• Как бы поздно ни было suggests a repeated situation: whenever it happens to be late
• всё равно reinforces a consistent pattern

So the sentence sounds like:

• this is what I do regularly
• even if I’m tired or it’s very late, I always make sure the cat is okay

If you wanted to describe one completed check in a particular past moment, Russian would likely use a different tense/aspect.

Yes, that is actually a very helpful way to think about it.

Although natural English might often prefer:

• No matter how late it is
• However late it is
• No matter how late it gets

the Russian structure has a slightly formal/literary flavor that matches English however late it may be quite well.

So as a grammar memory aid:

• Как бы поздно ни было ≈ however late it may be

That is not always the most everyday English translation, but it captures the grammar nicely.