Hey Joel.

"where the members differ in thickness more than 10% of the thicker, the cap sheet shall be the thicker"
This is a straight pull from 1595 fig 7

I think your read is the correct one.. (however, what does that matter in 3F eh?)

Your description appears to me to fall under a condition covered here:

5.7.5 Special applications. When none of the test welds described
above are applicable to a given production weld, a more limited welder
or welding operator qualification may be achieved with a test weld
consisting of the given production weld or a test weld representative
of the given production weld.

Typically in 1595, two tests are requred to establish a greater range of thickness qualification for welder performance.

5,3.2 Two test welds, each with members of equal thickness, shall
qualify welds with all intermediate thicknesses, in addition to the
thickness qualifications of 5.3.1.

So it appears to me, that the qualification test you have described is designed for a specialty production run or repair rather than an overall or general performance qual that would encompass a greater range of material thicknesses.  My admittedly conservative read would be that the record you have qualifies the welder only for a single project, part family or production run.

Edit:
Lastly keep in mind that in the 1595 world that groove welds in materials less than .063 do not qualify the welder to do fillets... Both grooves and fillets are required for production qualification if both will be done in production or repair runs less than .063.

"I_/ A groove test weld does not qualify for fillet welds in base metal"
equal to or less than 0.063 inch in thickness (see 5.5.1.1).