tl;dr: do not make the player the component owner
Last week I made three versions of this. The conclusion is that, due to the way component ownership, the cable attachment and simulation rules work, the best course of action seems to be making a dedicated actor that spawns cable components - an actor that is, ideally, not associated with the player in any way.
Here’s the dramatically simplified version that spawns cable actors instead:
- the cable actor:
- the function that gets relative transform of the component we’re attaching the cable to:
- the player placing cables in the world:
All in all, great exercise - I learnt a lot about what not to do. 
As mentioned at the start, I’d probably opt for another actor spawning just components. This way we wouldn’t need to worry about attachment rules.
If there’s a better way of doing the above, I’m all ears.