Not missing a script... let me make sure that I understand what you are doing and where the process breaks down. It seems like you:
- Shift-CMD-P to see list of commands.
- Type "etr" to select the "Export to Reminders" command
- Press "Return" to perform that command.
... and then get nothing?
When I do that sequence now I get another prompt that allows me to choose which reminders list that I want to insert into... though that behavior depends in a Preference. If you have "Always use Reminders.app > Default List" then that prompt will be skipped and the current selection will immediately be exported to that default list without showing you a prompt. I just tested everything again, and all seems to be working as expected for me on macOS 10.13.
Maybe the video tutorial linked in my other post to this thread will help you firgure out what's happening/going wrong. If not please let me know and I'll try to dig deeper. If it's not working can you take a screencast showing TaskPaper and Reminders app windows side by side when you try to export?