In my view if a brand is "revived" properly then it should have the feel of the original modernized to match todays styles. I am going by looks alone and not the writing properties of each brand. Both conway stewart and kaweco pens feels right. They do not feel out of place or too different to their originals. Thy looks basically like an updated version that the original company would make for today's market.
A Bad example would be Esterbrook. They do feel completely out of place when compared to the original and doesn't feel like something the original company would make if they didn't go bust. Shape, colors, overall feel looks all out of place. They may be attractive pens but it is very unlikely for someone to pick up a modern pen and think that it looks like a vintage esterbrook.
Onoto pens also feel a bit out of place when compared to the styling of the original but its neither here no there. it has some cues to the original, but also have some design cues from other brands such as croxley. When you look at a CS it looks very much like any CS. As long as it doesn't have a flag nib. Flag nib kills the look of it.