Easy mode -- don't bother 
Use Tab-delimited text and open your logs in a spreadsheet program for viewing.
Harder mode -- remembering that the thread is all about creating RTF rather plain text log files, this post has the macro and this one has JavaScript that writes to a file as well as setting the Clipboard.
Best mode -- skip log files altogether. This is perfect database territory, one document per record with fields to show progress and so on. You could roll your own version using JSON for storage and macros to CRUD with that file. I'd reach for FileMaker Pro as I already have it, but the free LibreOffice has an MS Access-alike or you go with sqlite and one of the free GUI builders, Mongo DB, web-based with Airtable, etc.