This looks like a really good system. I just have one small thing to add to it.
A lot of charsets aren't symmetrical. If this is the case, the event will need a different graphic, or it won't look like a mirror image. To create the proper charset, first individually flip each character image (of which there are 16) horizontally. Then just switch the individual graphics for left and right. Save this new graphic and use it for the event behind the mirror.
I know, it's not exactly difficult to figure out, but some people might not think of it, or might not be able to figure out how to flip everything without a lot of confusion.
Add it to the tutorial if you want, or don't bother. Just thought I'd point it out.