Pulling in more feedback from the call for testing from @getdave on this current experience:

Updating the Template Part Title under Advanced didn’t update the block toolbar or the list view name for the block. I expected this to show up immediately. Once I saved the template and the template part and then refreshed the page the title did eventually show up in those locations. In fact, it looks like both List view and Block toolbar components need to be force-rerendered in order to reflect the changes. Indeed, hovering over either one once the Title is updated will cause the change to be reflected which I believe is due to the re-render occuring.

Sharing more feedback from another participant in the call for testing:

When adding and naming the Template part, I can’t tell if the part has been saved and has the new name as there is no visual sign that a part of the template is there at all. That can be very confusing. I ended up with four Parts of template blocks, all stacked up and pretty much overlapping.

There were two participants who ended up with multiple template parts while testing.