You Give Me Fever
In your case, I guess it is a good idea. My stab at fantasy had me run into a similar issue that ultimate resulting in me decided not to write fantasy, but in that case it was over language, words that fell out of usage or whose meaning has changed radically. You still seem to be using modern English so I think it could work.
That's why he wants you to have the money. Not so you can buy 14 Cadillacs but so you can help build up the wastes
Zzzzzzzzzz
Just be sure to use the words in a way that context will make fairly clear what you mean by them soon after (or as) you introduce them. Readers aren't all morons, and if you give them context, they'll figure out what you mean.
...if you don’t love you’re dead, and if you do, they’ll kill you for it.
Veteran readers of speculative fiction are used to coming across words in the text that don't mean exactly the same as they do in everyday usage.
Thus the trick is to make sure your readers know it's SF before they open the book, and at they're veterans at reading it. And as another poster said, context.
My world building project is set a few thousand years after the end and after society has rebuilt itself into a low fantasy setting, with the occasional society quirks from being a modern society, rebuilt without all the technology. One of those quirks was having certain names for things that are common take on addition meaning since there was a stigma against using a more proper but less politically correct name.
For instance due to a fractured military stepping in and taking charge of various communities shortly after the end, the word commander comes to be used in the same context as the word king would be used in a medieval setting.
Another example would be Parties, as in political parties, being used in the same context where you would use noble houses in a medieval society.
I thought this would be an interesting way of showing linguistic drift by having some words we know of today take on new meaning in this setting. But I then thought that would make the setting to confusing, then I thought the viewers are Not morons, from there I flipped flop back and forth for a while till I decided to ask the question here.
Is using common place phrases from are time as inserts for terms in an after the end society with a medieval feel to it a good idea or is it needlessly complex.