How do I add a hero to the map editor?

I managed to add my own hero completely separately from the others. I can't say exactly how I did it, to be honest, but I can say the following:

1. I moved the .pak file with my hero separately from the game so that I could work on the mod without worrying about file names. I couldn't use the same names because the .pak file was in the data folder, which already contained all the configured files.
2. I initially followed the "Hottabych method." I did the first three steps and started the fourth.
3. I got lazy and didn't want to re-connect and re-configure everything. I closed the map editor and put the .pak file back in its place.
4. I went back into the map editor. I thought about it and added Resource =: Close MOD.
5. I opened the table and looked at AdvMapHeroShared, and there was a file for my hero. I started to get excited, but it wasn't in the editor yet.
6. Before all this, I was looking at how to get it into the game. I opened the MapFilters.xml file in the Editor folder in the root game folder. There, the heroes are taken from the AdvMapObjectLink folder.
7. I went into AdvMapObjectLink in the editor => MapObjects => _(AdvMapObjectLink) => Heroes => Inferno
8. I created a file called Andromalius.(AdvMapObjectLink) in the Inferno folder and linked it to Andromalius.(AdvMapHeroShared)
9. Voila, the hero is now in the map editor under .Heroes(Scenario), which is exactly where I wanted it.

I think that Close MOD is what helped me. After that, I did exactly the same thing that I was trying to do before, but it didn't work before. But now... it works.

Added 3 minutes ago
Also, a new index.bin file was generated in the data folder. I deleted this file yesterday, and it wasn't generated yesterday.

Added 28 minutes ago
A small problem appeared - the icon stopped displaying. But I'll figure it out somehow.

Added 15 minutes ago
The icon is now there, everything should be fine.

Added 8 minutes ago
...now it's disappeared from the editor. What the heck? Why is everything so messed up? I'll have to fight with this until everything is working properly.