Hello,
We ran into a similar problem. What we did was extend (old-school customization) the Case's Models/Collections and point the url or urlRoot to the SuiteScript 1.0 version of the Services.
Below are the changes we made, in this format: "*.ts File*" --> "Change Made"
Case.Collection --> CaseCollection.prototype.url = 'services/Case.Service.ss';
Case.Fields.Model --> CaseFieldsModel.prototype.urlRoot = 'services/Case.Fields.Service.ss';
Case.Model --> 'services/Case.Service.ss';
Hope this helps