Two sisters.. Elder sister organize parties and use that money to save the kingdom budget to help poor people. She is the MC While the other critizice those high aristocrat family for wasting money in parties. She is a straight forward character. Due to this .. the servant and guard say MC as a selfish and cold person.. Later she was sent to marry in another country... then everyone realizes MC effort calculating the budget and Taxes of their country
Warrior something Here https://www.novelupdates.com/series/the-magnificent-battle-records-of-a-former-noble-lady/
Sorry, I don't remember the title. The little sister is a self-righteous idiot hailed as a saint with a lot of idiotic friends: they are sjw in a medieval setting. The mc went to a northern country and she was the one responsible for the family's great prosperity but had a bad public image even if she helped more poor people than her little sister and her stupid friends.
Oh, I read this before now that you mention that. I'll see if I can dig it up later. I think instead of a sister it might have been one of those otome game MCs though
I think it's Koushaku Reijou no Tashinami. Chapter 25 has a similar scene to what you describe. I might check a few other candidates too.
^^, The Evil Lady Will Change seems the closest comic ive seen to what you're describing, but it's a manhua, not manga?
There are similar aspects but the protagonist and the girl popular for her deeds but blind to reality are not sisters.