According to Islamic Jewish students, if an agreement is made between the two parties and that agreement has some clauses offensive to the spirit of Islam, then the agreement stands and the clauses go. They are considered as omitted and not valid. So if, however unanimous the agreement be, I mean all the parties concerned may be Muslims and may unanimously agree to it and sign it, yet it will not be binding if they go to Qadha.
In case of disagreement later on, if they go to Qadha, Islamic court of justice, they would delete all those clauses which are offensive to Islam and read the agreement as if those clauses were never contained in that. This clause which speaks of fixed rate of interest is offensive to Islam, it will go. The only clause which will be left would be, they promise to share the loss, well and good, there is nothing wrong with that. If in an agreement, both the parties agree to share the loss, what objection can Islam have to that?