I tried installing Equilibrium - the result is zero. The game works perfectly, but Equilibrium doesn't recognize it at all. There are no updates in the editor.

If you mean Equilibris, then to install it, you need to install not only the mod itself, but also two more files - executable RAR archives, heroes4_sfx.exe and camp_ed_sfx.exe. First, unpack them into the game folder, and then run the mod installer.
As a result, you will have 3 executable files for launching the game: the one that was for Warlords/Armageddon's Blade, the regular Equilibris, and the Equilibris tournament version. Moreover, each version can only load saves that were made on it. Otherwise, the game simply won't recognize them.
In general, read everything about Equilibris here:
http://equilibris.celestialheavens.com/rus/faq.html

Added 5 minutes later

Now I've installed just Heroes 4 - now I'm thinking about what to do.

Hehe... install Warlords or Armageddon's Blade on top of it, then you can easily install Equilibris on them.:smile01: I'm not sure, but it seems you can also install it on the base Equilibris, but you need to patch it first - I haven't tried it myself:smile32: