That last one looks like it ends up being an over engineered version of simple springs - like I'm using in Constellation
Maintaining tension isn't difficult to set-up, especially in larger models using rubber, springs, weights, or cones (Jarvis winch), A little slack won't hurt anything so long as you consider it in your set-up - running things so that slack isn't a potential problem.
On the real boats, the hands on the cast-off braces let them run. One person will be there to watch for snags, and then take up slack and belay when each yard is set. To replicate that
you need the off-side winch to be free-wheeling with a little friction to let the braces out - then you need it to become rigid when its it's turn to haul braces in.
What you want is something like this YouTube thing, but that reverses the "rigid" and "sprung" drums when bracing the other way.
All that is multiplied where you're controlling multiple yards per mast. They each have their own geometry, and the larger the model, the more yards should be actively controlled - course and tops'l yards at the very least.