I don’t think CFA and Accounting Exams are directly comparable, since they focus on very different areas. Yes, there is some overlap, but because of the different focus, the difficulty will also be different.
CFA has the bigger focus on portfolio management, so even if CA have portfolio theory as part of the syllabus, it would make sense that CFA exams would cover this subject more thoroughly compared to a CA exam, and hence be ‘harder’. Similarly, CA have a bigger focus on taxes and auditing, so one would expect CA exams to be of higher quality for those subjects compared to a CFA exam. The same can be said about FRM, whose main focus appear to be derivatives trading. Even though there is an overlap with CFA, they don’t stand a candle to FRMs when it comes to derivatives pricing and exotics. FRM syllabus on this matter is simply stronger.