I don't think set-blend-time is for that. This is propably for use of AnimationTree and AnimationTreePlayer. these are nodes for blending animations and they use AnimationPlayer as a database.
Blending animations is mostly usefull in 3D, when using complicated rig interactions. SInce You want something easy like rotation and position change, You should just key it up with proper timing in normal AnimationPlayer frame editor.
Just add channel position and channel rotation and keyframe rotation 0 slightly before finishing keyframe of position, and final keyframe of rotation on the end of animation.