You are misinformed. Immortal Soul and temporary hell are core doctrines. If they say there is no hell, they are most likely referring to the xian and Muslim concept.
The Concept of Immortality
"No matter how the basic principles were reduced or revised, immortality remained a major tenet of Judaism."
I think rather you are misinformed. I already asked you to take a look at the original Jewish concept (Josephus version at least). Your information is very deceptive in nature. The Jews I contacted explained immortality and hell very differently (I perceive deception as well).
1. Now as to Hades, wherein the souls of the of the good things they see, and rejoice in the righteous and unrighteous are detained, it is necessary to speak of it. Hades is a place in the world not regularly finished; a
subterraneous region, wherein the light of this world does not shine; from which circumstance, that in this region the light does not shine, it cannot be but there must be in it perpetual
darkness. This region is allotted as a place of custody for souls, ill which angels are appointed as guardians to them, who distribute to them
temporary punishments, agreeable to every one's behavior and manners.
2. In this region there is a certain place set apart, as a
lake of unquenchable fire, whereinto we suppose no one hath hitherto been cast; but it is prepared for a day afore-determined by God, in which one righteous sentence shall deservedly be passed upon all men; when the unjust, and those that have been disobedient to God, and have given honor to such idols as have been the vain operations of the hands of men as to God himself,
shall be adjudged to this everlasting punishment, as having been the causes of defilement; while the just shall obtain
an incorruptible and never-fading
kingdom. These are now indeed confined in Hades, but not in the same place wherein the unjust are confined
The Works of Flavius Josephus.
Josephus' concept is close to it. However it may not be exactly as Josephus is never a Pharisee having a seat in the Sanhedrin.