Legacy of Shantiri

Also, according to the plot, Harold defeats Grover's army, but how would that look in the game itself? Should we make the player lose?

Whether to make the cutscenes a continuation of the action on the map or just insert them is up to the author.
For example, there is no need to conduct the battle with Harold in real-time; the player only has their army weakened. Harold approaches Grover, and a dialogue scene begins. Accordingly, the dialogue scene can be formatted as "caught-healed-released." You can make the scenes so that they don't jar the eye in any episode.

I fixed this problem, but it's strange... He cast either 1 or 2 spells. And in your case, he cast 3.

That's why the author's replay is interesting, so you don't have to explain it in detail.