Wikipedia calls him Hsu Hao-hung, with Taiwanese orthography, which they're probably obliged to apply universally to Taiwanese names.

But afaik, all Go discussion between actual players refers to him as Xu Haohong, with Mainland spelling (see the videos Kejie VS Xu Haohong and Park Jeonghwan VS Xu haohong, Eunkyo; and The Greatest Go Tournament Run Possible- Part 1, Telegraph Go, which labels him 'Xu Haohong' on screen).

I think we should keep Xu Haohong the title but note Hsu Hao-hung as an alternative form, and also make it an alias. Does anyone disagree?

Hsu Haohong should probably be an alias as well.