dang I feel you on that, I found this open source godot addon that is working towards an advanced movement system. Currently the project is lacking combos or combat mechanics, which is why I find your template really great! https://github.com/ywmaa/Advanced-Movement-System-Godot
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I will be updating my combat system to a more proper one, but in case you can't wait, the more proper approach should be enabling rootmotion on the attack animations so they don't feel this jiggly, and more polished blend values with some trial and error.
For a cleaner code you can make a state machine using enumerators, and switch between locomotion, rolling and attacking states etc.
Also you can use slerp for focus/lock on enemies.