I don't think I've seen such behavior, and I drive on multi-level roads almost every day. The car does slow down for the curves that it senses directly.
As for Maps improvements - they are completely separate from AP improvements. They literally work on separate computers with probably completely different codebases.
The Autopilot does seem to rely on information from maps (of some kind) to know when to slow down for corners. I say this because I've seen it slow before the corner begins, and before I've seen the lines of the corner on the instrument panel.
I haven't experienced it on I5, or 405 near me. Heck I don't think I've experienced it slowing before corners on any freeway/highway in WA. I had fun with it slowing for corners going over the pass in Southern Oregon though. From my experience the speed has to be set pretty high, and the corner has to be a pretty significant corner.
As to slowing for non-existent corners I haven't experienced this, but I believe WK057 has. I've also seen reports of this behavior from others. That's the primary information I'm relying on when I say that it's using some kind of maps to determine when to slow. I also know from experience in how it handles corners that it doesn't really see them all that well. If you've noticed it often has to keep doing corrective turns instead of one smooth turn if it's a fairly steep corner. I think it's a limitation of the single camera setup.
If it is in fact slowing for corners based on maps doesn't mean its the maps that's in the navigation system. It could be a completely set of maps, or it could be some kind of duplicate. We know Tesla is using fleet learning to build a set of maps. But, we don't know where these maps are stored or where the initial version came from.
Furthermore we don't know where the Autopilot will get it's information on when to impose the 45MPH limit. Does it get this from the navigation maps or somewhere else? Where does the Autopilot get the TACC hold time information from? As others have said this was woefully bad and completely wrong at times.
My primary desire is to have a good working Autopilot system where
1.) adaptive cruise control WON'T slow down for non-existent corners
2.) the TACC hold function works correctly with the proper hold time
3.) The speed limit information won't misinterpret a 65MPH zone as 85MPH. Or at least where information from the maps overrules it.
I do not want any restrictions on Autopilot, but I don't mind a limitation if that limitation forces improvements to the maps functionality of autopilot (and maybe Nav if the data is shared).
So I kind of see this as a win-win.
If it doesn't work this 45mph on surface streets limitation isn't imposed. Lots of things Tesla uses their beta testers to test out don't make it to the final release.
If it does work we have a better overall car.
Of course there is a risk they'll release it without making any improvements to what does the highway/freeway detection, and it will suck for all of us.