I was first attracted to DS's art style before I learned about the game content, thus I always care more about art style.
It's common to have multiple people doing different scenes in any animation production, but that's why character sheets and animation supervisior/director or lead clean-up artists exist to help remain the consistency. Shows like Steven Universe may vary from episode to episode because different sub-contractors are doing animation for each episode and different animation directors are supervising each episode, that's acceptable because it still remains consistency within one episode and characters don't suddenly change their style from scene to scene. Sometimes different styles by different animators even add more charming and personality if they are well planned and organized, like Bob Clampett's cartoons from Golden Age, or shows like Ren & Stimpy from 90s, or any modern "sakuga" anime shows.
In this case, the inconsistency is certainly not intented and pulls down the quality of animation. I could see animators for the Willow scenes don't even have a character sheet or maybe just being too lazy to follow the sheet. As an animation maniac who really enjoys animator's personality, I can certainly accept the isconsistency IF ONLY THEY ARE ANIMATED WELL. But these two Willow scenes didn't meet any standards of being well. I'm not sure if you can see the difference between the old DST trailer and the new ANR trailer, but I'll point it out to be clear: The lines of Willow in the old trailer is quite loose. Each body portions are composited well. The whirling pigtails add sharp contrast to the body for greater visual effect. The staging is well planned for a clearer action. That's what we called a good "cartoony" drawing, but everything lacks in the new Willow scenes. I know, the animators behind the scenes might not be that bad, they could be just too rushed or not used to draw "cartoony" stuff, but as a commercial product, customers don't care any excuses.
As for the new Charlie "design", personally I dislike it, but I'm not trying to convince anyone and everyone could have their tastes. However one thing should have been made clear: it doesn't fit the overall style of Don't Starve. It doesn't have a similar body proportion to other characters and it's too realistic for a surrealistic game setting. It's like having a character with Teen Titans design in a Teen Titans Go show, it feels completely off.
Also I'm criticizing the movement of Charlie in the opening scene. Let me explain here: The hand-lifting action is all wrong. There's too little overlapping in the scene, the head suddenly stops while hand keeps moving that makes Charlie really dull. There should be some more "holds" for the head and some overlapping for the body shifting to make movement more natural. Also the timing is too even, the animator should use tighter spacing for the beginng of action and wider spacing for the end to make the hand-lifting more dynamic. Not to mention Charlie's blank face...It's one of the worst animation pieces I've seen from Klei. AND IT'S THE FIRST SCENE! I mean, if you're really in a tight schedule for doing actual good animation, you should at least make your opening scenes looking good. Even some poor anime shows know to use their best animation in the opening!