Went to a temple in Taiwan several years ago and brought a jade pendant for luck. Was told to never let others touch it, or that my good luck would transfer to them. However, there was an incident where multiple people touched the pendant. Can anyone give advice on what to do?

Pure superstition.

Pure superstition.

"Pure superstition."

Yep

Even within Buddhist teaching, you would not lose the luck, but pass on to others.
(if one believes in luck) which of course luck is not a Buddhist teaching which teaches blessings of the various gods and karma along with rejecting earthly things and living a good and better life.

The jade was touched by many people, before it was boxed and sold in a temple. And by the way, Buddha would have been upset over the selling of products at a temple.