My way: I took 2 adhesive tapes (one is denser and more sticky, the second is small and transparent), then I cut out a small patch and sealed the middle contacts with the denser tape, then I pasted a patch of transparent tape over it. Cheap, good hold, easy to remove. Not felt by hand.
The transparent tape is bent a little from above and glued with the sticky side to the sticky one, forming a small grip for easy removal and re-gluing.
I also confirm the small sticker/tape on the two middle contacts is slowly coming off. Most probably due to cleaning and wearing. Those contacts remain a weak part of the Bangle.js 2 including the weak magnets of the charging cable that just helps a little to keep it in place. I decided to use the silicon cover and apply a bigger piece of electrical tape to cover all 4 contacts that I can easily replace if needed at every charge.