Re: As a new mystery begins in our Charlie Chan Sunday Comics...
Yes, I believe that there were instances of Charlie Chan movies being shown several years after their first runs. Probably this was not too widespread, though. It would be interesting to research this through vintage newspaper movie ads!
Your point about the Chan movies being translated into three languages for showings in Switzerland would mean that there were at least three versions of each movie. This would offer a logical place to consider the existence of one of the four presently "lost" Charlie Chan movies, perhaps.