Mirza Bashiruddin reminds me of a typical Sarkari Mullah. They talk like him in declaring all other people except themselves as Kafir, condemned to hell forever.
You are certainly contradicting Mirza Bashiruddin.
I am not denying the existence of the belief of degrees of kufr among Qadianis. They can believe in it. But this point of yours is irrelevant here because Mirza Bashiruddin, the second Caliph, is very clear in simple English about the status of non-Qadianis. He is talking not about Muslims, he is talking about Kafirs. Page 60 onwards in his book "Truth about the split", he says, tha those who deny the Prophethood of Mirza Ghulam Ahmad Qadiani are Kafir bil-ma'moor, and have destroyed their spiritual life, in addition to being eternally damned in punishment [ condemned to Hell forever ]
He is using the classical definition of who is a kafir, and what is a kafir's abode. He does not consider Sunnis as Muslims. He considers them as Kafir for hell-fire. This would be the Kafir of the highest level according to your levels.