It’s too simple and broad a question so I’m not going to give you a straight answer - sorry!
I presume by leaner you mean less body fat and more muscle?
Carbohydrates and fats are really broad groups of nutrients and we eat foods not nutrients. You’re better asking yourself what are the foods I’m eating?
To lose body fat you need to consume fewer calories, regardless of the source. This article can help you here: How to lose weight well | Huel Guide
If you want to gain muscle then you need to make sure you’re consuming enough protein and often you need to consume more calories than the body needs so the body can convert that excess protein and food into muscle. You can find out more here: How to Eat When Building Muscle – Huel
As you can see the two kind of go against each other which is why a lot of people go through shredding (losing weight) and bulking (gaining muscle) phases.
Similar to above it’s just too broad. Which carbohydrate and which fats? E.g. sugars vs omega-3 fats is going to give you a different answer compared to complex carbs vs saturated fat.
Huel v3.0 contains more carbs than fats but you’re right more calories come from fat in Huel Black Edition.
Hope that helps!