18912 is an Insider build and has an expiry date. You had asked if you would be able to upgrade again to 18912 if .NET remains not working after rolling back to 18362. The ISO provides the best way to do that, if you need to.
There is no point in using the ISO on the same build if it is already working well.
If you can roll back to the 18362 public build and keep .NET working, that would probably be best. But I don't know if that will work.
Rolling Back isn't a solution for everyone. The roll back did not work on 2 of the test computers we tried it on.
I have a mix of enterprise and Pro Windows 10 builds and they all have this .net Problem. I can't go with insider down load solution as some of the computers are production machines. I can't afford to have untested updates in them.
What is Microsoft doing to fix this issue it's not even on the https://docs.microsoft.com/en-us/windows/release-information/resolved-issues-windows-10-1809-and-windows-server-2019 that supposed to have known issues.