“If we assume that once there is a consensus on an Ikkar Emunah that that means that HKBH would not have allowed a wrong view to become consensus”
Even according to what you guys are saying, before the consensus, there are no taynas on someone who got it wrong. So you can’t use the fact that there is a consensus as a proof to who is right on the basis that HKBH would never let the consensus be wrong, because there wouldn’t be any problem if the consensus would be wrong – it would be the same as those who were wrong before the consensus.
In other words, your whole hechrech is that it is inconceivable that HKBH would allow the consensus to hold of heretical views yet that is not actually so inconceivable because there wouldn’t be any taynas on them for having the heretical views.