您是否尝试过以下方法：
创建一些自定义Keyword类，定义为：

public final class GeneralWebUIUtils { 

    public static int GetNumberOfWindows() { 
        return DriverFactory.getWebDriver()
            .getWindowHandles()
            .size();
    }

    public static boolean WaitForCondition(Closure<Boolean> onCheckCondition, int timeOut, Closure<String> onErrorMessage, FailureHandling failureHandling = FailureHandling.STOP_ON_FAILURE) { 
        boolean isConditionSatisfied = false;
        final long startTime = System.currentTimeMillis();

        while((!isConditionSatisfied) && (System.currentTimeMillis() <= startTime + timeOut * 1000) { 
            isConditionSatisfied = onCheckCondition();
        }

        if ((!isConditionSatisfied) && failureHandling.equals(FailureHandling.STOP_ON_FAILURE))
            throw new StepFailedException(onErrorMessage(this.GetElapsedTime(startTime)));

        return isConditionSatisfied;

    }

    public static boolean WaitForWindowOpenChange(int timeOut, FailureHandling failureHandling = FailureHandling.STOP_ON_FAILURE) { 
        final int initNumberOfWindows = this.GetNumberOfWindows();

        return this.WaitForCondition({
                return this.GetNumberOfWindows() != initNumberOfWindows;
            }, 
            timeOut,
            { double elapsedTime ->
                return "Number of open windows/tabs has NOT changed after ${elapsedTime} seconds";
            },
            failureHandling,
        );
    }

    public static double GetElapsedTime(long startTimeMillis) { 
        return (System.currentTimeMillis() - startTimeMillis) / 1000.0;
    }
}

然后，在你的测试用例中，像这样调用它：

WebUI.click(findTestObject('Pokus2/Page_Accounts - altFINS/Sergej'));
GeneralWebUIUtils.WaitForWindowOpenChange(15);

这将解决您的问题，如果不是仅仅使您的测试用例失败的话。
请查看代码，如果有任何问题请告诉我！

更新：我刚刚从你的评论中看到，你试图与之交互的输入按钮存在于一些影子根中。

在这种情况下，您需要create Test Object for the shadow root element, and then make the Test Object for it a child Test Object of that