Но он часто видел, как хозяин бьет

Но он часто видел, как хозяин бьет его сестру, и от этого мальчик жестоко страдал (и это заставляло мальчика жестоко страдать).

Results (English) 1:

But it is often seen as the boss beats his sister, and that the boy had suffered (and this made the boy violently suffer).

Results (English) 2:

But it is often seen as the master beats his sister, and this boy was suffering severely (and it makes the boy suffer cruelly).

Results (English) 3:

But it is often seen as he hits his sister, and of the boy has suffered (and this is forcing boy was severely suffer).