It is the nature of the texts that make decipherement difficult along with the fact that we don't know if the signs had the exact same values as Linear B. If we had texts that were long e.g. like hymns or poetry and knew the values of the signs we would be able to decipher it.
Also the so called Minoans are not 'CHG/Iran Neo', they are mostly ANF derived, over 80% (?)- I don't remember exactly.
Sorry for quoting myself but also not all CHGs were speaking the same language, not all EHGs were speaking the same language etc
Personally I don't associate early IE with CHG but one population assumed to be non-IE having something like ~20 CHG doesn't prove anything.