@Zalthos said
"Excellent notes on the first passage cited here. Have you any insight to add to I:38? I can't be sure if the teacher has control specifically over the merciful/severe transmission of the ordeals or complete control over the creation of the ordeals themselves."
FWIW my sparse notes on this are here: aumha.org/arcane/ccxx13.htm#38
Generally, no, the individual teacher doesn't provide these at all. That's rather Motta-esque. The teacher (i.e., Order superilor) has the task of delivering the system. But the Prophet was given a mandate to teach (compare Liber Magi) and control over the severity of the ordeals. This severity is still primarily controlled by the Beast - the initiatory-governing authority of the aeon.
Sometimes those in whose charge an initiate is placed will take upon themselves this judgment, leaning toward severity or mildness, but most of the time this results in problems. Chiefs of Temple of Thelema, for example, are instructed to simply "hold the walls in place," deliver the system as given to them, hold people on track to their own integrity and commitments. The best successes come when they do this exact thing, and little "speed bumps" occur if they try to go easy on someone or be overly harsh.