Autofill by Selector not working on all Pages

Normally, i Login to formbased login pages by executing the following:

cefsharp_browser.ExecuteScriptAsyncWhenPageLoaded("document.querySelector('#input-email').value='[email protected]';");
cefsharp_browser.ExecuteScriptAsyncWhenPageLoaded("document.querySelector('#input-password').value='mysupersecretpassword';");

But now i´m actually struggeling to login to a Page(https://lagerimgriff.app/login) on which the code above doesn´t work.

The Form is beeing filled with the Values shown above but injecting the Values that way or by ID, the Login-Form doesn´t realize any input, saying the field beeing empty.

I´m not a WebDev but it seems to me that there is some intermediate JS which is checking the Fields for validity(f.e. the mail must contain @ followed by a . ), maybe that is the Problem?

As this seems to be JS related i´ll tag it too.

Is there any way of archieving an automated login on that Page?