well she is known for being honest- well not so much anymore but before and even to other people she's very obviously bad at lying and is quite honest and usually means what she says, thus this childhood habit of honesty makes her more naive and more likely to say things out loud as established with Maylene.
that her just blurting out whatever came to mind is what made her and Maylene friends, and inspired her to be a reporter.
Connie needs to learn to shut up yeah but I don't think she should learn to lie better, I think it's a very well-established and very good part of her character. Honest to a literal fault. just like her dad but in her own way as she said before.
Connie is a Grail and while the story makes you think sometimes she's very far from it. she loves her family very much and definitely keeps her ideals about honesty. she just changed her perspective on it due to scarlet.
Gosh Connie isn't dumb or anything but she seriously needs to learn to shut up . Also hoping she learns how to hide her intentions/emotions more