My main issue with this approach is that it breaks the workflow into “a-sync” set of tasks:

This is kind of the way you depicted it, meaning, there is an an initial dataset, "offline process" (i.e. external labeling) then, ingest process.

I was wondering if the “waiting” operator can actually be a part of the pipeline.
This way it will look more clear what is the workflow we are executing.

Hmm, so pipeline is "aborted", then the trigger relaunches the pipeline, and the pipeline continues from where it stopped?
I think this should work out of the box (needs testing, but supported). A pipeline can be aborted and continued, and the trigger will just launch the existing pipeline Task (the one aborted).
Should work 🤞 🙂