APIs that return XML, JSON or other data interchange formats are not really designed to have their URLs loaded as new pages except perhaps in diagnostic situations as their response are not generally considered to be human readable. This of course applies to a=API_EditRecord (which returns XML) as well as the vast majority of methods in QuickBase's HTTP API. When this is done the common convention among QuickBase users is to redirect away from the XML response by using an rdr parameter. This is a hack from the 90s. You should be using script instead of rdr parameters to control what happens next after calling your primary API. After the API is executed under script control you can redirect to any page you want or chain other processing or API calls into the workflow.
Continuing to use rdr parameters and other crude redirection schemes will continue to hold back QuickBase's progress.
