Hi there,
This is Bogdan from Romania.
I'm a mechanical engineer - specialized in the industrial robotic field, 3D designer and modeler (from time to time and some projects I could make the functional prototype too).
I'm doing product design, industrial design, reverse engineering, ideation, etc.
I have over 15 years experience working on various systems/devices across multiple industries, from concept to launch.
1 - don't have experience in e-bikes but i hold a lot of experience in designing swappable devices, locking systems and modular devices...
2 - besides of what you already stated, the connector (between the frame and the battery) should have a compliance... can not make the battery tightly fit into the frame holder (you need some tolerance, thus, the necessity that the frame connector have a little "play" and centering means for the battery connector)
3 - the battery should have a kinda cradle to allows it to snap and lock and to accommodate the latching cylinder
4 - from the description, i see the battery get out downward - this means it is exposed to water and dirt, so you'll need a kind of sealing system..
Regards
Bogdan