Is it only me or fernflower does not put the code in the correct lines, and the debugging fails to navigate over the code in the IntelliJ IDEA?
[I work at JetBrains]
Maybe I'm just misunderstanding you, but even if the bytecode sequence is reconstructed as the original code that produced it, stuff like whitespace and comments are simply lost with no ways to recover.
(Also, local variable names, certain annotations depending on their retention level, etc)