Alright, there is a new discovery 
I managed to get a status update notificaiton, but it is camouflaged as new comment:
{
gid: ‘1198739731444968’,
created_at: ‘2020-11-26T17:05:23.449Z’,
created_by: {
gid: ‘60604372481597’,
name: ‘Simon Tretter’,
resource_type: ‘user’
},
hearted: false,
hearts: ,
is_edited: false,
is_pinned: false,
liked: false,
likes: ,
num_hearts: 0,
num_likes: 0,
previews: ,
resource_subtype: ‘comment_added’,
resource_type: ‘story’,
source: ‘web’,
target: {
gid: ‘1171144249301681’,
name: ‘Automated Ads’,
resource_type: ‘project’
},
text: ‘koische sache\n’,
type: ‘comment’
}
But I still couldn’t watch for new “comments” on “project comments/status update”. Any idea about this?