In that example the task items just need to be tab indented one more level to get the arrangement that I think you want. So like this:
Test-Project:
Sub-Project-1:
- New Task
Sub-Project-2:
- Test
Also when you have questions about the item hierarchy you can see what TaskPaper things it is by looking at the vertical guide lines in the editor. Any item that has child items will show a vertical guide line coming down from it’s bullet handle. That vertical guide line will extend down to the items last visible descendant.
I think perhaps the beauty of the TaskPaper format is that it is a completely consistent tab-indented plain text outline.
(Items at the same level of indent are peers, regardless of their item type decoration (hyphen or colon etc), and this allows, inter alia, for top-level miscellaneous notes, which don’t have to be involuntarily annexed by whatever happens to have been the most recent project)