Rolling that radius at a 2mm thickness isn’t a problem, nor is adding the flanges.
When fabricating spring steel you have to push the material a lot further than regular steels to get the desired profile, and can be a challenge to control depending on your press tooling and which direction the material grain runs. Your comment below sums up the solution though, get some materials and test it until you know what works:
To the OP, how accurate does your sheet metal need to be, what’s your tolerance? I assume this is a 1 off and not for volume production, do you need repeatability? Are you fabricating this yourself or getting a shop to do it?
Either way, if you go with spring steel make sure that it can be cold-worked. I also think you should design a better way to assemble your parts.