I don’t think so.
how are we so sure that this identity attribute transform you have written here within critical_attribute1_past stores the recent value?
Inside a static operation transform, all the variables must be precalculated and not null before a transform passes them to the velocity template with final value [and final value logic conditions like if else set contains foreach etc.]. Therefore, old identity attribute value will be collected before the velocity template rendering. Depends on used simple or complex business logic, you can define the needed, expected and protected target identity attribute value here to assign collected old idendentity value, or new value from source.
FirstValid operation transform operation is just a limited analogue of a well known multi source attribute precedence procedure.