No time, got to go, but it is great that you are brave enough to post pictures, because you never know what all anyone may say.
I would try one hole longer in the western saddle, so you can let your leg down a bit and sit more in the middle of the horse.
That bit on the paint is not really good for training, two or one handed.
Put it on your hand, hanging from the bridle held by the other hand and have someone from behind you handling the reins try to guide you and you will see how those bits just don’t work well at all, turn and twist any one way, not twice the same.
In the turn, the horse is not set right for the turn, he is straining, not turning back over his hind end.
Some horses are grumpy by nature, is the way they concentrate, some are mildly objecting to confusing signals, some to pain somewhere, you can find why he is showing light subtle resistances.
That would help make any horse more happy, although some, like people, just are too serious to lighten up.
I would check the figure eight/flash, seems a bit tight and I don’t like those with loose ring snaffles, conflicting the way those snaffles, a “noisy” type bit, that should be loose in there to work properly, should work.
Tight cavessons require a more steady bit, like a D ring snaffle.
I like your soft hands, the horse in that one stride seems not to be coming from behind right, so you are giving a bit to help him come thru.
Mostly, I love people working like you are there, with a good forward attitude.
I know anything we say from one picture may be the complete opposite in the next frame, so it has to be taken with a grain of salt.
Pictures are a moment in time and known to lie about what really happened before and will happen after.