No. Your Apple Health data stays exactly where it is, on your device and in iCloud if you sync it there. Deleting your Fulcra account doesn't touch it.
What gets deleted is everything on the Fulcra side: the copies of your health, location and calendar data that synced in, plus anything you or your agents recorded, including custom data types, annotations and files.
Worth knowing: your Context account and your Fulcra account are the same account. Deleting one deletes both.
Deletion begins after a 48-hour window, and once it completes we can't recover any of it. If you want a copy first, export before you start.