Okay, apparently Sense is quite picky about how you actually construct the formula, it just does not say so in the editor.
This -- finally -- worked:
If(RangeSum(Above(Sum(Meas1) / Sum(TOTAL Meas1), 1, RowNo())) <= 0.8, 'A',
If(RangeSum(Above(Sum(Meas1) / Sum(TOTAL Meas1), 1, RowNo())) <= 0.95, 'B',
'C')), (Dim1,(=Sum(Meas1), Desc)))
Moved the Sum(TOTAL ... ) into the Above() function and added exactly the right amount of parentheses in exactly the right places in the StructuredParameter. Why Sense does not complain when you write something that does not comply with the definition of a StructuredParameter I have no idea. Would have made things easier for me.
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