OK so let's be honest - these "Virtue Names" are basically like choosing Smurf names, and tieflings are way more emo than Smurfs. So listed "Virtues" include normal positive things we'd normally think of as virtues, but also things we wouldn't necessarily pick for a brainstormed list of virtues IRL, like torment, weary, creed, and despair. And, as you noticed, "carrion."
In English a "carrion bird", for example, is shorthand for a "carrion-eating bird", not a dead rotting bird. So you might interpret Carrion as Carrion[-eating]. Though if you're emo enough, both are fine interpretations as a tiefling name. "Eating carrion" can be seen as a virtue in terms of cleaning up the world, not preying on the living, recycling needed things back into the ecosystem, etc. "Being carrion" can be seen as mortification of the flesh, not valuing your lives above others, being emotionless/needless, etc. Or it might be as simple as "I like to KILL and leave bodies lying around." Don't be literal, be artistic and channel the impression the name gives you, that's enough.
But in general these are left to the PC to get all philosophical about, there's no "right interpretation." In reality it's a list of Emo Smurf names to pick from (and to let you know you can pick pretty much anything as a Virtue Name) because you think it sounds cool for a devil person.
Elf's Fey Ancestry is the closest I can think, but it is still immunity, not "resistance".
Fey Ancestry. You have advantage on saving throws
against being charmed, and magic can’t put you to sleep.
"Resistance"
Aside from that, "Resistance" against sleep is something hard to define, to begin with. It is not a damaging spell, so the common "resistance" = half damage doesn't apply.
It also doesn't require an Attack Roll or a Saving Throw, so disadvantage/advantage (respectively) also doesn't apply.
Because of these reasons, I don't think there is any kind of feature that mitigates the sleep spell - every entry I know of is either immune to it or not.
Little Frame Challenge: You want it RAW, but you are yourself using it for a homebrew, so I fail to see the relevance of RAW.
A simple feature that is somehow "equivalent" to Resistance would say something on the lines of
Putting this creature to sleep costs twice from the HP pool.
Best Answer
There is not an Engineer Background explicitly, no.
However....
And...
In short, backgrounds are flexible, and players are encouraged to work with their DMs to invent new ones if the ones listed in the book don't meet a player's wishes. After all, you cannot possibly cover every 'backstory' of an adventurer with only 13 (25 if you count SCAG) categories.
So, pick a background that is close to what you're going for, then work with your DM to customize it into exactly what you had in mind with your character.