on Android devices with API 31 the app crashes when using context menu. 

Actually this is the native android context menu which crashes the app, the RichTextEditor context menu is not displayed. 

The RichTextEditor context menu gets displayed when closing the keyboard and then tap on the text.

when using the justify toolbar item it does not justify the text. 

there is a mistake with the accessibility modifier for `Telerik.XamarinForms.RichTextEditor.RichTextPasteType`. When it is Internal it's not possible to use the PasteCommand since it requires that type as input. 

Solution:

use reflection to get the enum

var assembly = typeof(RadRichTextEditor).Assembly;
var type = assembly.GetType("Telerik.XamarinForms.RichTextEditor.RichTextPasteType");
var obj = Enum.ToObject(type, 1);
await Clipboard.SetTextAsync("A pasted text");
var canExecute = richTextEditor.PasteCommand.CanExecute(obj);
richTextEditor.PasteCommand.Execute(obj);