First of all, you should never use flipbook collision to attack lands. A Sprite can only have one collision in Unreal (unlike in 2D fighting games where there are hit boxes and character boxes). So this one slot should always have character collision. I see that you tried to make a sword swing but it will not work as you have all the collision set to “Block” instead of “Overlap”. Blocking will also have jumpy behavior as it is meant for blocking movement. The way you think is right, but the execution is wrong and it’s normal for a beginner.
Basically you need to keep collision for character only as mentioned above, and then use Trace Channels to detect a hit. Now the hardest part is animating hitboxes as you have to determine their size and location every frame so the Trace Channel follows the character as it moves. Red and Blue Boxes you saw in my youtube videos are basically moving MultiBox Trace Channels. This is what 3D games do aswell. All attacks are mostly trace channels that trigger every frame depending on the player position so the trace follows the player.
Now, since there is no anim notifies for 2D, you have to create your own system to trigger things every frame and check the key frame index at time. This is where everyone struggles and so I did for months before I figured out my own way.
Life of 2D is rough so, good luck.