You've answered your own question, stick with the Cannondale. It sounds like you enjoy riding it and it does what a dedicated gravel bike will do. Why change ?
I came very close to converting a 1990 Fuji steel mt. bike to a gravel. I needed a rigid fork (not cheap) plus knew I was going to have to finagle all the parts to work with STI type shifters and to make those work with V brakes. Road shifters are not matched to mt. bike derailers and brakes, so work was needed. Ultimately I decided too much work, get a gravel, which I did. You're C-Dale is ready to go.