En lo que respecta a la certificación, la revisamos.

Yes. En lo que respecta a is a set phrase meaning something like:

• as regards
• with regard to
• as far as ... is concerned
• when it comes to

It is best learned as a whole chunk rather than translated word by word every time.

It sounds fairly neutral to slightly formal, so it fits well in business or administrative Spanish.

Because Spanish often introduces a topic first and then repeats it with a pronoun in the main clause.

So the structure is:

• En lo que respecta a la certificación = topic
• la revisamos = main statement about that topic

That la refers back to la certificación.

This kind of repetition is very natural in Spanish. In English, we often avoid it, but in Spanish it is common and sounds normal.

Because la certificación is the direct object of revisamos.

• revisar algo = to review/check something
• so something is the direct object

Since certificación is feminine singular, the direct object pronoun is la.

So:

• la revisamos = we review it / we reviewed it

Using le here would not be standard.

Both are possible, because revisamos has the same form in:

• present: we review
• preterite: we reviewed

So only the context tells you which one is meant.

For example:

• In a general procedure: we review it
• In a past event report: we reviewed it

This is very common with nosotros forms in Spanish.

Normally, no.

Revisar usually needs an object, and in your sentence that object is la certificación. Since the noun has been moved to the front as a topic, Spanish normally keeps the object pronoun in the main clause:

• En lo que respecta a la certificación, la revisamos.

Without la, the sentence sounds incomplete.

A different sentence would be possible if revisamos had another object, for example:

• En lo que respecta a la certificación, revisamos los documentos.

But for the original meaning, la is needed.

Because the first part is an introductory topic phrase:

• En lo que respecta a la certificación, ...

The comma marks a pause before the main clause.

This is similar to English patterns like:

• As for the certification, ...
• Regarding the certification, ...

So the comma helps separate the topic from the main message.

In simple terms, lo que means what or that which.

Very literally, en lo que respecta a is something like:

• in what concerns/regards ...

But that literal breakdown is less important than the full meaning of the expression.

For learners, the most useful thing is to recognise en lo que respecta a as a single connector meaning regarding or as far as ... is concerned.

Yes. Some common alternatives are:

• Respecto a la certificación, la revisamos.
• En cuanto a la certificación, la revisamos.
• Sobre la certificación, la revisamos.

A few notes:

• en cuanto a = very common, neutral
• respecto a = also common, slightly formal
• sobre = more like about, sometimes a bit less precise in formal contexts
• en lo que respecta a = a bit more formal or bureaucratic-sounding

So the original sentence is correct, but it is not the only option.

Not always.

• certificación often refers to certification as a process, status, or formal validation
• certificado usually refers to a certificate, the document itself

So depending on context:

• la certificación = the certification
• el certificado = the certificate

In your sentence, la certificación suggests they are talking about the certification matter itself, not necessarily a physical certificate.

Yes, it does.

It sounds correct and natural, especially in formal, professional, or administrative Spanish from Spain.

That said, in everyday conversation, many speakers might choose a simpler version such as:

• En cuanto a la certificación, la revisamos.
• Respecto a la certificación, la revisamos.

So the original is natural, but a little more formal in tone.