let me give you a small piece of advice...

either make it all one campaign (which seems difficult for now), and release it as one campaign file, or refine the map and release it as a single RPG-style map with a well-thought-out plot and progression...

What's wrong with HotA as a mod?

some people like it, some don't...
1st - many changes (changing the order and cost of construction; introducing new objects)
2nd - personally, I really don't like the HotA animations; the animation speed-up in SoD is much better
3rd - balance changes for multiplayer, but HotA doesn't seem suitable for single-player at all
4th - new creatures: in HotA, they will be generated on the map
5th - animation that deviates from the canonical Heroes 3 (I still play with the original 16-bit graphics at 800x600 resolution)

and there are many other reasons; I don't want to go into all the details right now, but this is just my subjective opinion

Added 2 minutes later

It's all because of the objects in the first mission; I couldn't figure out how to bypass them realistically.

You can bypass them elegantly and tastefully - instead of using a HotA fence, use SoD's single rocks; the result would be slightly different, but overall it wouldn't be inferior to the original Heroes 3 compared to this HotA