The young Reds trailed 2-1 with 12 minutes remaining at the Totally Wicked Stadium in St Helens until a Neco Williams equaliser was followed up by Curtis Jones' superb 82nd-minute curler and a Rhian Brewster penalty.
Yasser Larouci had rounded off a superb counter-attacking move to put the hosts a goal up after five minutes of play.
But Karim Adeyemi equalised midway through the first half before Affengruber headed just after the hour mark to put the Austrian side ahead.
Barry Lewtas named a team that had plenty of first-team exposure with Ki-Jana Hoever, Sepp van den Berg and Harvey Elliott also in the starting XI.