Someone else in the comments touched on this, but I want to elaborate;
Even if Glis/Kris/Inglis could solve all of the kingdom's problems, she doesn't want to as she views it as not her problem. Her priorities are as follows:
1. Keep Rafinha and their Families safe
2. Fight Strong stuff
3. Get Stronger
4. Fight stronger stuff
???
?. Profit
She does not care herself about what happens to the world- she will do what Rafinha wants to do and will follow her into battle, so any attempts at winning Glis over to their side will have to involve Rafi. Though I'm sure if she sees Rafi going on a bad path, she'll stop her.
However, unlike most edgelord protagonists, she's not going to turn into the Demon Lord for her goal- that would mean harming her family. She's not malevolent or violent, she just wants a good fight.
Why? The kingdom she spent her entire last life making has no traces left of existing so far as we know, so all of her previous life's work was meaningless, so she decided to not bother this time around.