i'm being ... overly paranoid because of the huge changes to the underlying database structure.

Fair enough, but to my eyes your proposed tests:

my $list = $object->foundation_list;
ok( ref( $list ) eq 'ARRAY', 'returned a list' );
ok( scalar( @$list ), 'returned a populated list' );
ok( ref( $list->[0] ) eq 'HASH', 'first element is a hashref ...' );
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are less paranoid than the more concrete test:

is_deeply( $object->foundation_list, [ { ... whatever ... } ] );
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It does all the type checking and makes sure it's been populated with the correct values.