If this map is accurate, it really hammers home how needlessly isolated from the rest of the park Swarm is. The distance between paths on the Stealth and Swarm side of the lake is barely longer than the footprint of Flying Fish, and probably shorter than the queue lines of either ride. Would it really be that difficult to build a bridge?
As mentioned, not difficult, but until they use the adjacent island for something, logistically impractical.
Yellow - Logical area for where a bridge entrance by Stealth could go
Red - Area designed for a connecting bridge from Swarm island
Any connection between the two areas would have to use the adjacent island, there's no way they could link it to Swarm's island elsewhere (unless they physically built a pathway over the ride, which just wouldn't happen).
It's simply just impractical to create a pathway on that island to connect to two areas up, plus do associated CCTV stuff. Too much cost for too little reward. Better to absorb that into a larger project when they open up that island with attraction(s).
Again, as discussed, there was early plans that that island would house a roller coaster to be built in 2015/6. Those plans changed instead for a dark ride, since it was decided the park needed a dark ride over a coaster. The area was again considered for a coaster in 2020, before that whole project was cancelled thanks to Merlin reducing spending in the theme park division. I don't know how seriously a coaster was considered there for 2024, but I'm sure there would have been conversations.
When it will happen is too hard to know. Certainly it makes sense that the next major investment would open up there, but it depends on when that is and what happens with other rides in the central area of the park.
As for Hyperia, here's a couple more photos of the lift hill crest from yours truly: