CR 120.4a Excess damage is damage greater than the creature’s toughness, taking into account damage marked on that creature and other damage being dealt to it at the same time as this damage. Any damage greater than 1 is excess damage if the source dealing that damage has deathtouch.
When you cast Lightning Bolt targeting Kambal, Kambal's ability will trigger and resolve before anything else.
Jaya has a replacement effect that changes how damage from red sources is dealt, and Toralf has a triggered ability that triggers when excess noncombat damage is dealt. Lightning Bolt would deal 3 damage to Kambal, but because of Jaya's replacement effect, the damage is 4 which is 1 more in excess of Kambal's toughness. This triggers Toralf's ability which can target Emrakul because it is an ability, not an instant. Jaya's replacement effect will affect Toralf's ability because it is a separate event causing damage from a red source; Toralf's ability would cause 1 damage but is changed to 2. Because Toralf has deathtouch, 1 damage from Toralf is lethal damage so Toralf has dealth excess damage which triggers Toralf's ability again
Compare CR704.5g, and CR704.5h, and look at CR120.6. It's troubling that the only reference to deathtouch being lethal damage is in a rule that is just talking about "if an effect that’s causing damage to be dealt states that excess damage that would be dealt to a permanent is dealt to another permanent or player instead". That isn't the situation for Toralf.
120.10, for Toralf's effect, is conspicuously different from 120.4a - it doesn't mention deathtouch. The rules for combat damage don't mention deathtouch. CR702.2c (Deathtouch) is even more conspicuously specific about how deathtouch is not construed as lethal damage in general.
There isn't a formal case for the Toralf damage being lethal in this instance. And excess damage is defined in terms of lethal damage, so the triggers stop there (with 2 damage dealt to Emrakul and Emrakul dying).
Thanks! I see now between 702.2b and 702.2c how the dealing of damage because of an ability or spell is different from the assigning of combat damage. That further clarifies the deathtouch/trample interaction during combat because you may assign 1 damage from a creature with deathtouch. Toralf isn't a Super-Duper Death Ray lol. Damage doesn't kill things, state-based actions do.