I've been searching online about the "ST-Link V2 ISOL"'s schematics and seems like nobody has done the work for it. So I decided to do some probing on the board.
Here is my result, some components are ignored such as TVS diode and bypass caps.
If anyone else got a "ST-Link V2 ISOL", feel free to help completing the schematic. Peer review is always nice.
Still haven't quite figure out how the isolation work on some lines exactly.