Patchouli Knowledge has had multiple portrayers, initially being MysticAlice and then Black Dragon Sol. The role was transferred to Voile Witch, who had the role from 2013-2015, which now it's back to Solar.
Being a character from the Touhou series, most of Patchouli's portrayal is as accurate as her creator ZUN had put her. To even the attire. Whereas in the fan-interpreted past of Patchouli in Black&White was developed as a concept by Black Dragon Sol. In her youth, Patchouli had worn a Trinitarian cloak along with a white blouse, the cloak would reach down to above Patchouli's ankles. Where her shoes would be at her feet. She also always had her grimoire on hand, which would be the book which Patchouli uses as a weapon in IaMP/SWR/Hisoutensoku. Because of Patchouli's youthful appearance despite her actual age, combined with her power as one of the greatest magicians - Black Dragon Sol had opted to give her the look of a woman in her mid-twenties.
Being dominantly true to the foundation of the character, however. Patchouli had kept her stoic face and behavior, although only showed her unguarded side to her children. The story between them was meant to replicate a long-lasting tragedy, and a reason as towards why Patchouli stays locked up in a room. Eventually, the wounds healed upon finding her children again is only really minor. The main reason as towards why being that it's (her shut in behavior) something that Patchouli had done since her children had been sent away. Patchouli's thirst for knowledge becomes present in her own children in turn, ensuring a legacy of sorts, while still keeping true to ZUN's original design.