It a very common issue with the application developed using non-native tools. I have faced this kind of issue and there isn't anything you can do about it from your side(Automation script). You need to consult with the developers in order to make the changes on the UI elements. We opted out from automation for the App developed with xamrin because the changes are just to support automation and does not bring any value on the actual application. You should look into automation tools provided by Xamrin itself.
If you still need/want to continue with Appium then you should combine it with any image recognition tools i.e. sikulli.
Thats the conclusion I have with application developed with cross-platform tools, I'll be happy to check out if someone has solution for this.