Playing devil's advocate here about adding in smells; terpenes are not just everywhere, but in many of the products we eat, drink, smoke, inhale, etc.
The real issue here is the source of the terpenes and how they are being added in. Concentrated terpenes can make you very sick, which is why it's nearly always suggested to be added in lesser amounts to help negate potential side effects (not greater amounts. Less is MORE here.)
Not all terpenes are created the same either; there are natural sources and synthetic versions.
But yes, you can 100% add terpenes to cannabis flower.
I don't think I would go to the kitchen cupboard to try to enhance my weed though. Look at vanilla extract for example; smells great right? Not a terpene. It's an aldehyde, which are organic compounds that can damage cells and DNA when smoked (lots of aldehydes in cigarettes for an example.) And that's such a easy thing to mistake based on the innocence of just not knowing, right?
So you -can- play science here, but don't play guessing games with what can potentially make you (or others) sick!