You can render text with the CraftAR Augmented Reality SDKs for Android, iOS and the Cordova plugin for Augmented Reality by creating an image with a transparent background and your text. This can be done dynamically since the SDK allows to programmatically load any content.
Also, the CraftAR SDK allows to customize AR contents (see Tutorial: Customize AR Contents in CraftAR).
In the case of the CraftAR Unity SDK, we provide examples (see ExampleDownloadContent in the distributed unitypackage) where we load a text resource into the AR scene.