Actorul improvizează sub reflector ca și cum ar fi la premieră.

Because -ul is the Romanian definite article attached to the end of the noun.

• actor = actor
• actorul = the actor

Romanian usually does not put a separate word before the noun like English the. Instead, it adds the article to the noun itself.

Improvizează is the 3rd person singular, present tense of the verb a improviza.

So it means:

• eu improvizez = I improvise
• el/ea improvizează = he/she improvises

Here it matches actorul, which is singular.

A rough pronunciation is im-pro-vi-ZEA-zuh, with the stress on zea.

A few useful points:

• z is pronounced like English z
• ea here sounds like a diphthong, roughly ya/ea
• ă is the Romanian schwa, a short unstressed vowel, similar to the a in English sofa

So the last part -ează is a very common verb ending in Romanian.

Here reflector means a spotlight or stage light.

In other contexts, reflector can also mean a reflector in a more general sense, but in this sentence the stage meaning is the natural one because of actorul and premieră.

Because Romanian often leaves out the article after a preposition when the noun is being used in a more general or idiomatic way.

So:

• sub reflector = under the spotlight / under spotlight
• sub reflectorul = under the specific spotlight

In this sentence, sub reflector sounds more general and stylistically natural. If you wanted to point to one particular spotlight, you could say sub reflectorul din stânga = under the spotlight on the left.

Ca și cum is a fixed expression meaning as if.

Even though și often means and, in this expression you should understand the whole phrase together:

• ca și cum = as if

So do not try to translate it word by word. Just learn it as one unit.

Because after ca și cum, Romanian often uses the conditional to show something imagined, apparent, or not necessarily real.

So:

• ca și cum ar fi la premieră = as if he were at a premiere

This is similar to English using were in as if he were... rather than as if he is...

It gives the idea of comparison, appearance, or unreality.

Ar fi is the conditional present of the verb a fi = to be, here in the 3rd person.

Relevant forms:

• aș fi = I would be
• ai fi = you would be
• ar fi = he/she/it would be
• am fi = we would be
• ați fi = you would be
• ar fi = they would be

In this sentence, it means something like were / would be, depending on how you explain it in English.

Here premieră means premiere, especially the first public performance or opening night of a play, film, or show.

Because the sentence is about an actor and a spotlight, the theatrical sense is especially strong.

So la premieră suggests the excitement or importance of a first performance.

These forms are related, but they do not mean exactly the same thing.

• la premieră = at the premiere / on opening night, in a general event sense
• la premiera piesei = at the premiere of the play, more specific
• la o premieră = at a premiere, one among many
• în premieră = as a premiere / for the first time, which is a different expression

So in your sentence, la premieră means he is acting as if he were at that special kind of event, not necessarily naming which premiere.

In this sentence, it sounds mainly literal: the actor is physically under a spotlight.

But Romanian can also use spotlight language figuratively. If you want a more clearly figurative idea like in the spotlight, Romanian often prefers:

• în lumina reflectoarelor
• în centrul atenției

So:

• sub reflector = very physical, stage-image feel
• în lumina reflectoarelor = more idiomatic for public attention
• în centrul atenției = in the center of attention

Yes. Romanian has several natural alternatives, depending on style.

For example:

• Actorul improvizează sub reflector de parcă ar fi la premieră.
• Actorul improvizează în lumina reflectoarelor ca și cum ar fi la premieră.

A few notes:

• de parcă also means as if, and is very common
• în lumina reflectoarelor sounds a bit more idiomatic than sub reflector in some contexts
• your original sentence is still perfectly understandable and natural

So the structure is flexible, but the original version works well.