Right now you can add custom fields in HR and sync these to CDS. However, unlike in CDS it's impossible to add calculations etc. to these fields and you need to add these custom fields manually to every environment.

In CDS it's possible to define a solution as extension to the HR solution with custom fields. It would be great if these solution fields along with the calculations and business rules sync to Talent.

Currently the work around we use is to create custom fields in Talent, deploy our solution to CDS and create business rules to then set the Talent values.