This looks like an incorrect solution, since there is no order for identity attribute calculation, how are we so sure that this identity attribute transform you have written here within critical_attribute1_past stores the recent value?
Representation:
Identity Profile Mapping:-
Critical_Attribute1 => Mapped to critical Attribute1 of authoritative source.
When the aggregation runs, your crtitical_Attribute1 becomes the latest value, so if you refer this within your transform, it will be a new value not previous non-null value.