The walkthrough is optimized so that if you follow it you will get the harem ending without issue. However, there will be points in the game where there is no right or wrong answer and is more of a "choose your poison" moment. Hasil v. Hasler is one of them.
If anything tho, the "consequences" mentioned in the walkthrough will likely be on the state of the server when we eventually return to it in a future update, and not that it could lead to losing a girl's path in the future (the walkthrough will warn players beforehand about it if that were the case).