I agree with you, but I think I may have misunderstood what you wrote. It was @jessegrosjean who made the of only using relative dates only on queries by saying,
It would be therefore very reasonable to suggest that those relative times are converted into absolute dates by the TaskPaper engine. I am imagining that this would required the new engine and a way to parse the info as it is typed into TaskPaper, and that is something that may be coming with TaskPaper 4. And that is what I mentioned in my post.
Now… according to your approach. I gathered that you wanted TaskPaper to do this in the background. Is that correct? Maybe I misunderstood, but don’t you think that this is something better handled by something like a program that checks for changes and then runs a Script in those changes?
Something like, http://eradman.com/entrproject/ would help you then. I am not sure if you can do that with Mojave and the file permissions; but I know you can use Hazel to run a script when your files change.
Because what happens if you are using your iPhone as you mentioned in your series of steps, but you don’t open TaskPaper in your computer for a couple of days? Now all of your dates are different than what you meant when you used your phone to add that to your TaskPaper file.
Maybe if you are using your phone to do this, Drafts would be the way for you to do it. That way you can simplify your steps. You should really check it out!
I just don’t think that TaskPaper should morph or add a whole different program that runs in the background looking for a series of changes in a file (imagine trying to set that up) and then format something when that is something that is available now by other mature programs that have that as their emphasis and offers more power to their users.
I might have misunderstood you, but if you have a questions, clarifications, or more suggestions, share them again. I would like to help, and I hope that letting you know about these programs help your workflow.