Having reviewed the photos and compared with photos of Squacco Heron (and Indian and Chinese Pond Heron I am fairly sure that this is just a leucistic Chinese Pond Heron unfortunately.
I cannot find any plumage of Squacco Heron (or the other Pond Herons) where the streaking on the underparts is diffuse and buffy. On Squacco Heron the streaking is limited in extent (usually not in the centre of the breast) and quite narrow but nonetheless very well-defined on sides of breast, neck and crown.
Mike Leven
