Populate Text Fields with dynamic data in API call

Hello!

We have a need to pass dynamic values that would reside within a Text block, essentially passing a reference name and account number. These values would change for each transaction, and would ideally be embedded in the longer text area as such " [Reference Name] has added you as a User on Account [Account ID]".

We are currently using a Template with preset Signer fields (some text, some list) and using the API to pass the Signer data and Send the transaction. This works well, but is there a way to inject the above mentioned dynamic text into the Template so that it Sends with the proper data listed inline with a section of Text?

Would it make more sense to do this via Text Tag Extraction, and upload a 'standard' document with dynamic Text Tags as opposed to using the Template?

Note: The Template is currently using  Word document, but I could change that to PDF if that helps.