Their spark is reincarnated to a life of endless suffering, humiliation and not being able to shoot straight as a vehicon.

 

That is illogical though. Many times have Transformers stated that their fallen comrades have became one with the Matrix, or Allspark. I mean, they have some sort of an afterlife.

 

This. Everything else sounds ridiculous. Only Primes can merge with the Matrix, that is the only sort of afterlife that you could imagine for dead bots. (although they are kind of not so dead in the Matrix, as their program code and memories are obviously inside the Matrix).

 

It could be interpreted that they have no actual afterlife, it's just that they believe there's one. An afterlife doesn't have to exist for someone to believe in one.

I mean, of course it varies from continuity to continuity, 'cause some of them do have an actual afterlife (like that one time Rhinox journeyed into it to save Primal), so I can't really talk for all of them but whatever.

 

Some bots may believe in the "Covenant of Primus", some may not, that's just my opinion so thats why some Cybertronians don't mention one.
Maybe all Cybertronians go the Allspark to be judged and break off from there?

 

It could be that the allspark cleans sparks of their past transgressions like the faiths that have reincarnation.

 

Beast Machines basically said so in no uncertain terms.
Primus breaks off a piece of himself and imbues it with some unique character traits, and sends this Spark out into the world to learn and grow and explore. And upon death, they rejoin Primus their stories, knowlage, and experiences become part of him. The spark loses its individuality in the process (this last part was mentioned in the TF Legends book) and the cycle continues. There are few exceptions. BW Rampage (spark was literally destroyed). G1 Starscream (immortal) , BW Megatron (tampered with the Oracle and mutated his own Spark), and Prime Megatron (dark energon infusion while still alive)

 

Optimus Primal merged with the matrix, and he was not a Prime.

 

I think there is no hell like what Jews believe

 

Where in G1 is this stated? I'm more of a G1 comics guy than cartoon, but I don't believe Allspark and such theological notions were mentioned in the 1980s ("Til All Are one" is too vague to count as a definitive example) - this sounds like retroactive stuff being added in.

 

Beast Wars/Beast Machines created the concept of the Allspark, as well as sparks in general.