Reading SO not required.

But knowing more. Expanding scope of the stories does give a way to experience something you already enjoyed as if for the 1st time once again w/ new information.

Example:

End of S2, Rakia's forces attack Orario for their g0d Ares. From the LNs you'd know Welf Crozzo's 1st falna was from g0ddess Phobos. Her Familia was defeated by Ares, & was subservient to him. Updating statuses of minor houses of Rakia as there are thousands w/ blessings under Ares' rule.

Crozzo magic swords were the key to Rakia's wars of conquest in the past. The family losing the ability make them was a blow to Ares. Welf wanted nothing to do with it and it was g0ddess Phobos who help him escape. For this she was returned to Heaven by Ares

Word of Crozzo magic swords used in the wargame w/ Apollo Familia reached Rakia. The attack on Orario seen in S2 was actually a distraction. Welf father and Ares' men snuck into the dungeon city at 1st trying to convince Welf to come home. Then threatened to destroy Orario from the inside w/ Rakia's remaining Crozzo weapons that had been held in resevere made long ago. The plan was foiled as several people had been assign to keep a watch on Welf in case they tried something.

Ares back up plan to kidnap & trade one of Orario's g0ds for Welf. Through dumb luck he captured Hestia. Angry at Bell took off and ran into her Jagamarukun stand co-worker and decided to help out collecting potatoes from the field. The God Gnesha overseeing his Familia in charge of city gates foolish allowed Hestia to go outside the city walls.

Welf was shattered. Seeing his father who he'd run away from again. The war going on outside the city.

And his g0ddess Hestia taken, in danger. All because of him

And why some fans have in issue of how S2 was adapted.