I made some decent progress today and I'm quite close from the end I think. I beat the hard version of the owl, which took a bit more than an hour. It's not an easy fight, but once you learn all the moves it's definitely feasible. I think what really enabled me to beat him was understanding that the best thing to do during his sword combo is to just dodge back and bail out when he does the shoulder charge halfway through. Trying to deflect the whole thing is too risky because of the firecrackers at the end and almost always backfired on me.
I then beat the Corrupted Monk really easily, the first two phases are pretty much free, it's just the last phase you need to look out for.
I also started getting rid of those shichimen warriors and headlesses. They are such pains in the ass lol. I killed one of each today. The shichimen that appears in the double ape boss room is a real asshole, sometimes he spams the laser beam up to four time in a row.
The area after the Corrupted Monk is a massive pain as well. Strong enemies absolutely everywhere, miniboss galore, double headless at the bottom of the lake... I'm calling it a day, I need to send in a job application this afternoon haha.