I'll try and explain this as best as I can, since I made it.

MCEs of single player enemies can be made functional in multiplayer mode by some method. It varies between the enemies. However, the events needed to unlock the MCEs in TSF are almost always completely different from the ones used in 1.23. In this screenshot, Violet was on my 1.23 server using 1.24 and Project Controller 4 to change the version. The thing you're looking at appears to be a fully functional standing monkey event on 1.23, but when viewed from TSF, it looks.. like that, I guess.

It might be fun to experiment with other MCEs like that some time. Who knows, we might even discover something useful...