Hi,
It seems like this project was designed with an old version of Ride and the first time you change the target processor, it incorrectly reinitializes some of the options, including the startup. This is what explains your build problem.
We will correct the project in the zip. In the meantime, you can simply restore the startup options:
"Use Default Startup" -> "No"
"Startup file" -> "$(RKitLib)\ARM\CircleOS\application_startup.o"
Then it will build.
There are no peripheral differences between the STM32F103VE and the STM32F103VG. So there is only the CircleOS elf file to change in this situation. No change in the code required.
If you were changing from a STM32F to a STM32L as you mention in your other post, (or from STM32F1 to STM32F3, or ...) then it would be much more different as I explain in this same other post.
Look at the devices datasheets and reference manuals, from the ST website, to know the differences between the devices.
Best Regards,
Vincent