So, I went to the site (rpacrm.bubbleapps.io) and the index value is in fact 9. You can see this when you view the html (right-click inspect)
What you need to do is include the parent element. This will help make sure you get it right every time.
In the selector you can add information about the parent element.
<html app='chrome.exe' title='Bubble Application' />
<webctrl tag='DIV' innertext='First:' class='bubble-r-box' />
<webctrl tag='INPUT' type='input' />
By using the innerText of the parent element (First:) you’re pretty much guaranteed to select the correct element.