I read a lot of webtoons and have seen a lot of meek FLs. I really don't think Ludis is that frustrating at all. Like all of her timidness 100% makes sense for her character. she literally had 0 power both politically and physically to the point she couldn't even protest being kicked into a hole and sacrificed. Even now her power is entirely reliant upon a sketchy and fickle old god of destruction. Despite this she managed to successfully negotiate her way out of the castle and to the worst hit zone and personally went in to assist with the demon raid. She's getting work done by herself in her own limited way. Would it be great if she ordered the god to kill her dad and sister for her? yes but also she is a kind and timid person. Killing an emperor would shake the country and even if he is an ass he is her dad and its hard to order the killing of anyone let alone your own shitty dad and bitchy sister. She has also only seen his power used twice and it was terrifying how overwhelming it was. Considering she dosn't know why he favors her I think she is in her right to be cautious with him.
Honestly what I think makes timid fls truly annoying are the ones who just sit around and cry. Or ones who make their situations worse for themselves and everyone with stupid choices. Or the ones who are painfully naive and ovely forgiving. I really don't think Ludis fits any of these categories. I reskimmed through the chapters and the first thing she does when she wakes up is send away all the new people trying to butter her up and stands up for herself against her dad and sister. She then vows not to forgive them and leaves the palace as soon as possible which is hours after waking up and getting beaten. She then talks back to the emperor and even blackmails him into forcing him to accept her conditions. She also immediately prioritizes helping the people and ridding the land of monsters over her personal vendettas. Considering its been about a week since all this started she is doing very well for herself. She also has not cried once after all that. So while she isnt the strongest or bravest I really don't think its that fair to be so harsh on her.