If I accidentally Reload the Create Instance page, I appear to lose my data

Summary: That is, Reload creates another Instance, which is almost never what I want.

This is related to Refresh page loses data, where Alexx pointed out that he's accidentally hit Refresh multiple times. Regardless of how his data-loss bug turns out, you will certainly appear to lose your data, and will create a spurious new Thing in its place.

The right answer is probably to change this flow -- the Create "page" should just do the creation, then immediately reroute to a new Edit Instance page, which just contains the Instance Editor. (Or possibly the new Thing Page, with the Instance Editor pre-opened.) That way, Refresh would produce the expected result, rather than duplicating the edge-trigger.