Huh. Well I'll definitely need to break that math down later, but as it stands, I do want to ask if you're alright with PCs starting with Nulls in everything but Body, because it means that picking the Body Gift is a lot more powerful, and any PC who doesn't take a gift which boosts Spirit or Fortune is effectively locked out of those actions from the starts, since nobody starts with a Grade in a Tech, and if they have a Null in stat they're rolling on, they effectively have 0 dice.
EDIT:
So gonna do some quick napkin math:
The chance of getting a single success for a Disciple which did not pick a Friend and is rolling using a Clay Grade stat is 50%.
If they choose to spend an Auxiliary to enhance their main, this chance of getting at least 1 success rises to 65%, with a 15% chance of gaining 2 successes.
A Disciple which took the Body gift has a 75% chance of getting at least 1 success with just a main action, with a 25% chance of getting 2 successes. If they double up with an Auxiliary, this gives them an 87.75% chance of getting at least 1 success.
A Disciple who has a friend helping them has a 70% chance of getting 1 success on Body task, being boosted up to a 85% chance with an Auxiliary, but these chances can only exist for a Body Task, since picking a Friend Gift means you only actually have Clay Grade Body.
Conclusion: Having a Friend or taking a Body Gift gives you a large advantage when it comes to succeeding on a Body Task. The only advantage that taking a Spirit/Fortune gift offers is the ability to actually roll for those tasks. Taking a Tech manual gift leaves you with the least chances of succeeding, and limits you to only being able to complete Body tasks.
Should note that Jolly Cooperation changes the math significantly, though only if the people cooperating actually have at least a Clay in the stat they're rolling for. Doesn't matter how many disciples cooperate if they all have Nulls in the relevant stat with no Techs.