PeterBartholomew1 I'd be one to support a uservoice request for handling of nested arrays in formulas.
Referring to the PooledPresents.xlsx sample file, and without fully grasping the logic, the following appears to return a 2d array:
=SUMIFS(INDIRECT("PresentContributions["&Contributor&"]"),PresentContributions[Buyer],Payee)
as does substituting the INDIRECT portion of the formula with something along the lines of:
OFFSET(PresentContributions,,{3,4,5,6},,1)
Unfortunately one is not able to substitute a non-volatile equivalent such as:
INDEX(PresentContributions,,{4,5,6,7})
A request for a complementary XINDEX function that allows for multiple ranges might be a possible compromise for covering such use cases more efficiently and transparently.
Microsoft