External regression testing of an Appian UI?

I would like to automatically regression-test an Appian App. The idea is to populate a dynamic, nested, conditional Appian UI with minimal to no changes on Appian side. Test cases have to be defined in AzureDevOps and using Selenium is considered an option.

So far, I see two alternatives:

1. I could image to define a REST-API for the corresponding form, if that is straight forward. By straight forward I mean that only a few lines of configuration on Appian side are allowed. The challenge is the current architecture of the interface with submit-buttons on a parent form and data to be entered in an interface nested inside the parent UI via rule-input.
2. We tried to use Selenium (without any changes on Appian side), but the trouble is to identify the buttons or to populated the pull-down menus etc. since all elements have names which change between deployments of environments, as far as I can tell. Is there a way to inject an additional, constant, user-defined CSS-property to each an every element in Appian's automatically generated output in order to make the identification easier?

Which other options did I miss? I of course read about https://community.appian.com/w/the-appian-playbook/2304/automated-testing-with-appian-selenium-api but it is unclear to me how much effort on Appian-side of the architecture this requires, and how it would integrate with AzureDevOps.

Any help is appreciated!

Related question which did not help me: https://community.appian.com/discussions/f/general/12758/find-elements-in-interface-selenium