I don't see how this is any different from alignment. The Sherriff of Nottingham is (presumably) LE and locks people up. Sahuagin are LE and sacrifice people to their diabolic deity.Okay, so no one can touch their hoard. They're possessive. Doesn't really tell me much about how they go about doing that, what they will do if someone does touch their hoard. Have the perpetrators thrown in jail? Eat them? Force them into a contract of service to pay for their sins? What if their hoard is safely tucked away and unthreatened. A group of people come along and ask for aid? How are they likely to react?
Devastate the countryside? What if you have a legion of faithful followers? What do you eat if the countryside is devastated? What's the reasoning behind it?
For the imp, if they aren't harvesting souls (or if there is no option to do so) what are they doing? When harvesting souls do they use trickery or a contract with fine print? How do they interact with other imps or those more powerful than they are?
If an imp isn't harvesting souls then what are they doing? I don't know - other than they're not doing their job - but I don't see how being told they're LE would help answer that question. I also don't see the contrast between trickery and fine print - the latter just seems like a particular case of the former. How do they interact with imps more powerful? Maybe they trade them souls, maybe they suck up to them, maybe they try to backstab them - wouldn't it vary from imp to imp and occasion to occasion?