Using pipelines to log the date/time including the seconds of a record change

I have a pipeline that logs when a record was changed in a tracker table. I need the date/time of the change to be accurate to the second. 

I can't have a pipeline copy the Date Modified of the source record to a Date/Time field in the status change record as we would lose the seconds.

I can't use the Date Created of the record created by the pipeline as this and the user's action are offset by a second or two. I need this to be when the user made the change, not when the pipeline created the record.

I created a Formula - Date/Time field in the source table that is ToUnixTime([Date Modified]), then the pipeline copies that to a Number field in the status change record. This works, however I'm in search of a more elegant solution than creating a formula field in every table that needs this.

Is there a Jinja expression that will give me the ToUnixTime() of Date Modified without having to create a formula field?