Does one know a time frame when this will be fixed or a work around?
Hi Trisha,
Actually the Survey123 website now already supports IWA authentication since 3.2 release on Jan 31, 2019. You can see the reference to this in the What's New here: https://docdev.arcgis.com/en/survey123/reference/whatsnewsurvey123.htm
Unfortunately, the known limitation on the following page (which I assume is where you got the bullet point from above) in the doc was not updated in time, so will be updated for our 3.4 release and this limitation removed:
Phil.