Hello Patrick,
When you run a module on its own, it always uses parameter values that are specified in the “Parameters” tab or the “Edit parameters” dialog.
The “Iterate” action doesn’t modify parameter values, stored with a called module. It merges parameter values, specified in the action properties, with parameter values, stored in the called module. And executes the module with the merged set of parameters.
The only way to see parameter values which were actually used to execute a called module it to make that module fail and then press “Open module” button in the error card:
As for the question about the “last_version” value - you can you the following function instead of the one that you are using currently:
format(date({File validity from as string},"yyyyMMdd"), "yyMMdd")