Yeah, referred pain is weird. When people have hand RSI the root cause is much more likely to be a shoulder/neck/postural thing rather than a hand thing. Its unfortunate 'carpal tunnel syndrome' has become such a widespread diagnosis when IIRC something like 1% of issues are actually due to the carpal tunnel itself.

To use a web analogy, its like having a broken button on a webpage and thinking it's a problem with the HTML (the hand) rather than with the server (the neck area).