Despite my Held Saal in my farm acc is at 8, I cannot split a single Hero Medal, to get the Wisdom..

Not sure if I understand the question exactly but here is how to split a hero now. Open the heroes menu and tap on the her that you want to split. The hero must be 'Free' so you cannot split a hero that is currently stationed or in an APC.

At the bottom of the hero screen are 2 icon buttons. Tap the book icon on the right to open the skills page. If the hero is 'free' you will see a small button on the upper right that has a face and a small x. (it is very small). Tap this to split the hero.