Basically echoing Ramhound's comment above and agreeing with it: Microsoft Word is suggesting these grammar fixes because they are indeed errors in the grammar.
They might be the way you speak or write, or they may be relics of the formatting of the document (we don't often say "and point H is ..." so the document might have some formatting for comprehension that breaks the thoughts up in a way that makes correct grammar more awkward.
But the point remains, the highlighted sections in the document sample you have provided are indeed grammatically incorrect.
The first one is because the section starts off mid-sentence. "Or" is a conjunction, a combining word, that goes between clauses inside a single sentence. You do not begin a sentence with "or". While the highlight is on "really piss", the root of the problem is that you've structured this sentences, from the outset, incorrectly. You can begin the sentence with "accordingly" or another word that has a similar meaning but is appropriate for the beginning of a sentence.
The second one is because "according to" should never end a sentence. "According to" always requires a following "what": "According to this document", or "according to Benyamin", or something similar. "According to" needs an object to be complete.
The third one is because the comma is unnecessary to separate the clauses of the sentence.