You should be able to load uV4 projects into uV5
Most of the F4 code/peripheral demos are very portable. You might have to adjust for specific pin/package usage, but this is not an unduly difficult task for an embedded development engineer.
I think the middleware mechanics are a bit more complicating than cutting and pasting a few files. I would recommend looking at working board examples in uV5, and how they are constructed. Keil might also have documentation related to building packages.
For commercial projects discuss with your FAE, and perhaps look to hiring contractors with specific experience.
Previous post for context
https://community.st.com/s/question/0D50X00009nK6yFSAS/board-support-package-for-stm3240geval-board
