I think that Está seguro, would be better for "It (the bolt) is secure."
I think ¡Verdad! could mean "truth" in limited American idiomatic use. In some casual, regional slang, after a person says something others find to be a profound truth, and they agree that what s/he has spoken is truth, they might respond, "(It)'s truth!" followed by a fist bump &/or nodding of heads, just as a short way of saying, "That's the truth!"
There was a trend about 20 years ago when people might say "Word!" to show approval &/or agreement for a truth that was spoken, in much the same way. It was even said by the actor who played the son of the Danny Glover character in a "Lethal Weapon" movie, then awkwardly repeated by the father, who was trying to speak the son's slang to seem "cool."
It was mostly urban use, from my understanding, so not widespread enough to commonly use, but just to point out that it was used for a time in that manner.
En ingles, "Its is right" es como decir "Esta es correcto" en español. In English, "It's" means "that thing is" or "That has" or "It is" if used as a contraction. "Its" means "That thing is owned by that other thing". http://www.its-not-its.info/ What is your native language? Someone here might be able to translate more accurately.
Pking, verdadero rather means "real, true, genuine" and it's mostly used as a descriptive adjective:
- amidstad verdadera - true friendship
- Los rumores son verdaderos. - The rumours are true.
Cierto is more along "right, true, sure". They are close in meaning but have different applications. You can say "Es verdadero", but it's far less common than "Es cierto".