Kape,
Changing the namespace of the project changes the Type Name of the various artifacts in your project (i.e. schemas, maps etc.), however you’re right about orchestrations – the Type Name here is not changed and does need to be changed manually.
However, there is no need to go into the .cs files generated from the orchestration – these are automatically generated by the X:ANG/s compiler every time you build the orchestration. Instead, open up the orchestration and go into the orchestration properties window (the part where you create new messages and variables etc.) and change the Type Name (and Namespace if necessary) there.
Bear in mind that if you already have an orchestration that is referencing maps and/or schemas (through ports for example) and you change the Type Name of those artifacts, your orchestration will complain and fail to compile. You will need to update these references to point to the new {Type] names of your artifacts.
HTH, Nick.