Going mainly off of memory here, but it's a fun little theory I learned about in high school AP psychology that propositions there are 9 types of intelligence rather than just a general concept of intelligence, and people have various strong intelligences while they may struggle in others! Originally the theory proposed 6 I believe but now it's up to 9. The types are:
1. Spatial-visual (thinking in pictures/charts, visualizing, artistic intelligence)
2. Verbal-linguistic (verbose, good writers and speakers, linguistic intelligence)
3. Logical-mathematical (pattern recognition, equations, scientific/mathematical intelligence)
4. Bodily-kinesthetic (motor skills and coordination, hands-on activities, dexterous, body intelligence)
5. Musical (tone recognition, talent for understanding musical structure, musical memory)
6. Interpersonal ("people smart", conflict resolution, communication)
7. Intrapersonal (highly self-aware, introspective, informed on their own reactions and motivations)
8. Existential (awareness of situations, theory, existentialism obviously, philosophy)
9. Naturalistic (natural pattern recognition, also hands-on activities, categorization)

That being said! I'll pick at least one but ideally two strong intelligences for each sinner.

Yi Sang: Logical-mathematical and existential
Faust: Logical-mathematical, probably intrapersonal
Don Quixote: Bodily-kinesthetic
Ryoshu: Spatial-visual
Meursault: Verbal-linguistic (because he's good at memorizing information and informing), intrapersonal
Hong Lu: Interpersonal, spatial-visual
Heathcliff: Bodily-kinesthetic
Ishmael: Naturalistic, verbal-linguistic (also good at memorizing and communicating information, as we've seen a couple times)
Rodion: Bodily-kinesthetic, interpersonal
(Bonus- Sonya: Verbal-linguistic, existential)
Sinclair: ... is difficult. Spatial-visual I think.
Outis: Verbal-linguistic, bodily-kinesthetic
Gregor: ALSO hard. Sorry. I'm really not sure I have one that stands out for him. I'd say intrapersonal but Gregor is more like someone who thinks he's self-aware when he genuinely really isn't and bodily-kinesthetic I feel like does not apply to him (and is also kind of a copout at this point)