Posts from RTF is a global modification that replaces all towns in the game.

When will the Sorcerer Eagle be added?

It will be included in the next update.

You need a black transparency. That is, 0,0,0 for RGB and the alpha channel should be fully transparent.
When you use the eraser in Paint or Photoshop, it creates white transparency (ff,ff,ff for RGB, but with an alpha channel), and the game interprets this as a white color. As a result, you get a lot of white spots.

Instead of erasing with a rubber, cut out pixels and insert them onto the base with the correct transparency, for example.
As a base, there were empty icons somewhere in the data.pak, you can use them. Or you can create one yourself – in Paint.NET, inverting pixels with white transparency successfully creates black, for example.
In general, there are several ways. And check the color of the pixels as usual, with the eyedropper tool.

What else will be in the next update, and when will it be released?:confused:

At a minimum, replacing the 1st, 6th, and 7th tier creatures with Cabirs, Djinns, and Griffins respectively would be good, and ideally, in addition to these changes, it would be nice to see a Citadel, a Swamp (territory for the Citadel), new mines with resources, a new city for Dark Dwarves, and of course, the magic needs to be "polished" (descriptions of silences, some abilities, etc.).
But when the update will be released is unknown.

By the way, who should be the basis for the Cabiri? They should breathe fire. The dwarven dragon is more similar to them, but it's too big.

They don't necessarily have to breathe fire; they can also throw spells, so I think Orcish warriors would be suitable. I saw magi made using them in NCF, and the idea stuck in my head.

In my opinion, the mages looked strange.

Well, I'm out of ideas, so who else should I work on?

What if we mess around with the models of mages/archmages? It should result in a simply beautiful animation of them casting fireballs.

I doubt it will work, but even if it does, the animation will look a bit strange when they just stand there (the wizards are holding a scroll in their hands, but the Cabirs have nothing).