The latest Xamarin.Forms (18.104.22.168452, just released) requires, for Android Pie, the latest Android Support Library series (22.214.171.124). Upgrading all these in an Android project using Telerik will not build in VS 2017 until the ancient Xamarin.Android.Support.V8.RenderScript, not available in that series, is removed. Unfortunately Telerik requires that dll for some controls. Although the project can then build, it crashes on trying to use a dependent control.
To put it another way, it would seem Telerik needs to remove its dependencies on RenderScript, seeing that Xamarin has not seen fit to update it.