"Sleep training" is, in my opinion, a myth. This has gradually dawned on me after reading many books on it and observing a couple of generations of young families. Sleep "optimization" is worth working toward, and that generally entails making the baby as relaxed, secure and comfortable as possible.
Some babies do give up and sleep after crying it out for a few nights. Others feel only mounting distress and loneliness from night after night of suffering on their own. But a child under 6-9 months does not have the capacity to understand the whys and wherefores of the parents' need for sleep. They sleep as well as they are able. They wake and cry for attention or comfort when they can't sleep.
They may be hungry, or teething, or the wrong temperature, or have some random pain or discomfort disturbing their sleep, and there's nothing they can do about it except cry. Sleep scientist now believe that even young babies can have disturbing dreams. Some babies become reactive to chemicals in their environment – perfumed laundry detergent, and especially fabric softeners, are pretty toxic and best kept out of a child's life. They can powerfully stimulate a baby's (or an adult's) nervous system.
If your baby cries for 4 hours before giving up from exhaustion, I wonder if she's being traumatized, physically or emotionally. It seems to me that she's desperately trying to tell you she needs comfort or food (growth spurts often increase nighttime hunger). Stress hormones that build up for hours night after night can actually change the size and function of certain structures in her little brain, and this will not serve her well later in life.
Some babies sleep easily. Some never do. Many change patterns several times during their first 2-4 years. Not much is known about why different babies are so different, other than they just are.
Babies seldom respond well to abrupt changes, like a cold-turkey dropping of the swaddle. You mention that she outgrew and hated it – there are larger swaddling cloths available, and more gradual ways of discontinuing use, like wrapping more loosely or leaving one arm free during a transition period. I wonder if you tried those intermediate steps.
I wish I could tell you there's some fail-proof system to get your little one to sleep. But some babies are higher-need, and that's one of the challenges parents face when deciding to have a child. My grandson was pretty easy in most ways, but was a terrible sleeper until age 2.5. It wasn't until then that his parents were able to leave chronic sleep deprivation behind. Now he's a champion sleeper, and the hard nights are a distant memory.