Translation:The five talented actors performed as guards in the theater.
To say that "the five talented actors acted AS guards in the theater" is different from saying that "the five talented actors acted LIKE guards in the theater." In the first sentence, the actors could be doing side work as guards, while in the second sentence the actors are merely acting like guards, while not actually being guards.
You would only need to use "geaktoroj" if it was necessary to indicate that there were both male and female actors in the group. Usually, "aktoroj" is sufficient. After all, the English word "actors" says nothing about the sex of the thespians, but most of the time we don't find we need to put "male", "female" or "mixed sex" before "actors", and even the word "actress" is falling into disuse.
I think I just wanted to know about the flexibility of the prefix "ge-".
But if you were writing a story or article about acting in the 1700s, you might want to use "geaktoroj" to emphasize the use of both male and female actors, as opposed to when Shakespeare was writing and all "aktoroj" were male.