kendo.diagram.Path is an object that can be appended to a kendo.diagram.Group object and supports such things as SVG paths. This is undocumented and unsupported functionality that can be accessed in pure JS but is inaccessible in TypeScript. Can you please support this object and add its declaration the d.ts file?
Given your explanation, I think this can be addressed promptly by the dev team, and does not need to stay on our feedback portal to processed when it gains enough votes. David, can you please report this omission via our forums or support ticketing system on telerik.com? Thus it will be reviewed and tackled swiftly. Thank you for your cooperation.