If her last name if Chang, it’s unlikely her name is spelt in pinyin. Otherwise her last name would have to be one of those more uncommon 常, 廠 type last names.
Assuming that is her last name and it’s in pinyin, than maybe Cho can be 綢 or 愁. 常愁 sounds like one of those names you’d find in Wuxia novels.
More likely her name is spelt in WG or even non-Mandarin systems.
If it’s in poorly rendered WG, where ch can be both ch and zh in pinyin, and o can be both e, o and uo, then maybe her name can be 張卓, assuming her name is spelt in Mandarin
JK Rowling is an idiot and an overrated writer. On the other hand, isn’t this a bit of an example of biting the hand that fed you? Yes, Cho Chang is an incredibly dumb name. Still this JK Rowling-written story led to a movie, which led to an incredible opportunity for her to get cast in a blockbuster series, become a minor celebrity and get paid a lot of money. Where was her outrage about this dumb name when she was cast for the part? She didn’t seem to have a problem with it then.
Also, I don’t like her lumping JK Rowling’s idiocy in with combating the very real threat of police brutality and racism. It diminishes the seriousness of the latter cause by watering it down with this silly fluff.
It is also possible her dad spelt his name in WG, and named her in another Sinitic language when Cho was born in England.
In that case her name could be cho in Hokkien, which would give you 張奏 or 助.
Maybe she has one of those composite last names common in early Hokkien/Austronesian customs. So maybe Cho-Chang are her full last name, and people just been calling her by her full last name.
In Cantonese her last name could be 曾. In Hakka her last name could be 鄭. Many Asian British people are from Singapore, Malaysia or Hong Kong, and they are likely to have names in Hokkien, Hakka, or Cantonese instead.