During the interview, they determine whether proper matter and form were used during the NO ordination, but the primary concern is if the priest and / or bishop had the proper intention. Most often, it is this "proper intention" problem of the priest that determines whether or not the priest gets conditionally ordained.
I fixed it.
They seek to determine if the priest himself had the proper intention, Brent said that many NO priests did not have the proper intention at their ordination - that's due mainly to the way they were trained in their seminary - "some seminaries are known to be more problematic than others."
The only way to determine the intention of the bishop who performed the ordination is if he said or did something outwardly that was obvious to all that he had an improper intention. So they are mainly finding out about the priest's intention, not the bishop's.
As I said in the OP,
"trust the SSPX, they do what they can to make sure there are no concerns about the validity of any SSPX priest." And,
"The SSPX takes the Church's position that the presumption is the New Rite of Ordination is valid."Because the NO Rite of Ordination's validity is presumed, the proper intention of the bishop is presumed - unless, like I said, the bishop said or did something obvious during the ceremony that showed he had improper intentions. *That* is doing what they can.
And because they presume validity of the NO Rite, they presume the NO bishop who was consecrated in the NO Rite who is doing the ordination, is also valid.