10wk kitten and resident cat fight

We recently adopted a kitten, he's about 10 weeks old now. We also have a 6 month old ginger boy who we've had since he was 8 weeks old. He loves people, loves to hang out with us, loves to play.. a lot. Hence the second cat.

We've had him for 2 weeks, we've been keeping it nice and slow.., did a face to face earlier, and went good. did another recently, and our resident cat just kept going and going, trying to play with him, kitten kept screaming, hissing to stop, resident cat not listening. We did this face to face while our resident cat was exerted to try to keep him chill.

We've been scent swapping frequently, site swapping frequently, they eat with the door cracked just fine, they show all signs that they should have supervised time together -- it goes well for a while, with treats as distractions, play time, etc.. but eventually it will just devolve into our resident cat not backing down when play fighting with him.

Our resident cat doesn't really show many signs of being annoyed, except for his tail swishing (but only when they're actively "fighting"). While doing the meetup, our resident cat doesn't really get distracted by toys while they're in the same room together, only treats.

The kitten doesn't run off and hide, he doesn't try to withdraw, he just looks fearful with his ears down, vocalizing to our resident cat, and then eventually hissing.

Do we go back and reintroduce? What will change? What could we be doing to keep things civil? Do we keep these interactions going, and separate them when it gets a bit too far? IS it too far?