Can flash and shutter release be triggered simultaneously with the Neewer 3-in-1 remote controls?

It is extremely unlikely that even if the remote control could trigger both camera and flash, they are in sync.

Remember that there is a (small) delay in pressing the shutter button. The only way to reliably sync the flash with the shutter button is for the camera itself to fire the flash.

If you have managed to trigger both of them, it is very likely that the flash fires before the shutter opens.