Can I politely suggest you spend a few weeks reading up on what's gone before so you don't get lynched asking questions like this?
The reasons for the original setting of the rent have been dragged over. In a nutshell:
PWKH claims that CCFC were offered a sliding scale when discussing the rent, that they chose this rent as it was the same as the cost of HR in the final year (as for how it was set) and we guess that CCFC thought they'd be back up to the Prem in no time and quids in.
PWKH also states that CCFC have never made a "serious" attempt to renegotiate the rent until last year, suggesting it's not as big a problem as some state (also CCFC themselves said it wasn't an issue a couple of years ago). There's evidence of Robinson "having a word" but nothing else. Some take this to mean PWKH is lying, I take it to mean that as stated it wasn't a full blown effort but rather a casual question (read the board meeting minutes to make your own mind up).
ACL have seriously restructured over the last couple of years, partly because of the CCFC situation but also because they were looking to expand anyway. ACL offered a rent of £450k when Sisu first asked for a reduction. Sisu rejected this as it didn't contain the F&B revenue they wanted in it's entirety. ACL initially said that was the lowest they can go then CCC restructured the debt to give lower outgoings and ACL came back with an offer of £150k (also rejected). Recently ACL have offered through the FL rent free this (last) season and (I think) £100k/year for the next two years while CCFC build a ground. This was rejected because "We can't deal with the council".
The general consensus is that the rent was high, but it's not 100% clear as to why the club agreed to it and Robinson/McGinnity isn't talking. However, the general consensus (outside of Nick and Grendel) is that when "seriously" asked the council offered a lower rent, three times, and were rejected in each case, so you've got to question the validity of CCFC's complaint IMO.
Welcome to the fun.