dertfgy I don't see anything in your dxdiag that would point to a Sims 4 issue, but it does list two crashes of the USB 3 driver. So it would be best to unplug all your USB 3 devices and restart the computer. You can then reconnect them—the restart usually fixes this kind of issue.
The TS4_Launcher_x64.exe is supposed to be present on any Windows install, although I don't have a Steam install handy to compare it with. I believe it has something to do with telling the game whether to default to DX9 or DX11 mode, as that's when the .exe appeared, but I don't know for sure. Regardless, it's clear that this .exe doesn't play much of a role in running the game, in fact I think it's not active at all after the initial load process. So the fact that it's missing for you is probably irrelevant and almost certainly unrelated to what's going on in your save.
If you did want to try to fix it, I'd suggest uninstalling the game and reinstalling to a different location, more specifically into a folder you create for just this purpose. But you don't have to if you're not seeing any negative consequences other than the notifications.
