So I just found out the su-37 never went into production and Was cancelled all together. It’s a shame really because it’s one of my favorite aircraft from ace combat
The problem the Su-47 was the forward-swept wings. While great for agility, the stress on them would likely have resulted in a very short airframe life.
The YF-23 lost to the YF-22 because it was less agile. Since the F-15, the USAF has prioritised agility over speed, due to the lessons learned in Vietnam.