I've never been a fan of James and my opinion of him hasn't changed much.
In contrast to his sister, he learnt nothing from his time in Bath. He is a sadder but not a wiser young man.
That line, 'Poor Thorpe : is in town, I dread the sight of him; his honest heart would feel so much...' always leaves me wondering how James can still be so blind to JT's charecter.
Maybe he's in denial.

I'm somewhat disappointed with James too.
Potentially, he maybe a better person. If I may put in a word for James- I think he has some redeeming qualities. He is not greedy, he was genuinely appreciative of his father's marriage terms for Isabella. He is well meaning but weak.

I agree he contradicts himself a few times. He may feel 'raw' but one of James' problems is he still doesn't know his own mind well.
James did not behave as a good brother in Bath.
I would've thought better of him if he'd apologised to Catherine-yet I doubt he realizes he ever caused her any grief in Bath.

In my view, the worst thing for James is to retain any acquitance with Thorpe.
Especially if he truly wishes to forget the sister.
Once Catherine is married, she'll encounter difficult family dynamics. One will include brother James and his relationship to his Tilney brothers-in-law.
Yet later, Catherine & Henry could benefit James- I agree he still has much to learn about people- he needs good, sensible friends.