That could explain why deutschunplugged (DU) has more Comments-Rewards. DU of course receives more beneficiaries than I do :-)))

You are using the rewards_api/getAllRewardsSums to request die rewards. For me, the answer for 30 days is ( I'll leave out the irrelavant ones):
{'author_reward':
{'sbd': 18.555, 'steem': 0, 'vests': 92582.178837},
'comment_benefactor_reward':
{'sbd': 0, 'steem': 0, 'vests': 0},
'curation_reward':
{'vests': 123554. 692384}}

comment_benefactor_reward has nothing to do with rewards for comments, of course. So the term "comments" should not be used. At the moment, I haven't seen any query that could distinguish this. Posts and comments themselves are only distinguished on the chain by the property "depth".