Hello there @Axoleis !
While I’m not familiar with the style of animation you are aiming for, I have experienced the relation between UE and Blender regarding animations, it’s not the best.
In case you encounter any mismatch with your animations when transferring them between the platforms, the first approach would be to reset export/import settings in both UE and Blender.
If the issue persists, then please follow the method detailed here. And as for alternatives, I found Maya to be more stable to work in combination with UE.