Can someone explain why there is such an obsession with creating ISOs. Slipstreaming ISOs, especially on the cusp of a new release of Windows 10, seems a bit impractical. If you want to get to 18363.4XX, all you need is a V2 1903 ISO which loads 18362.356, run the entitlement package which transitions to 18363.356, and then run the 418 and 446 updates. A homebrew 18363 ISO is hardly necessary. Just be patient and wait for MS to release an official 1909 ISO, if you think you need it.