The issue is that 'justice' is focused primarily on intent, not outcome. Whilst there are some 'offences' where outcome has more weight in English law, it is mainly intent. Also, in English law, mitigation is also established, but, remorse and character tend to have little weight, except where an early guilty plea is entered, which results in a 50% reduction. Thus, plenty of precedence for the way the RFU system is set up.
Whilst the hearing may have heard the 'good deeds' and letter from Eddie, I doubt that they made one scintilla of difference.
The failure lies in the inaction of other referees who have let Farrell get away with past misdeeds. That is not the fault of the panel.
It is what it is, an imperfect system.