Orders arrive at once; your own edits wait
The two paths through Squarespace run at different speeds.
A sale on either side reaches the other in about a second: Squarespace announces its orders immediately and so does the register. The slower path is stock you edit by hand inside Squarespace, which it tells no one about; we pick that up on our next look, a couple of minutes later.
In practice that means recounts belong in one place. Adjust the number in QuickSync or at the register and both sides carry it; adjust it inside Squarespace and it arrives on the next check.