Thank you very much, sork96! I managed to do it.
I don't know if you need this information or not, but just in case, I'll write it down. Maybe it will be useful to someone else.
So, in these main HDB files for each map, you can change a lot of interesting things, even without any in-depth knowledge.
For example:
- you can completely change the heroes on the map (stats, spells, skills, etc.)
- you can specify a list of available spells for the mage guild for each Castle on the map (so that only these spells appear when building)
- and most importantly for me, you can specify/change the list of all available artifacts and spells on the map (for Castles, only their spells are specified, but if you specify it for the entire map, it will work for Castles and for all sources of spells in general) - in this way, being a supporter of the idea of максимально original campaigns, ported to Tribes of the East, I simply removed all the spells + artifacts that appeared in Lords of the North (for the original campaign) and in Tribes of the East (for all campaigns). It doesn't matter if you use the RoM remaster or that very first port that is already several years old; in all of them, new spells and artifacts were added to the original campaign and Lords of the North, which always saddened me. For example, spells like regeneration, vampirism, or 3 summoning barriers were not in the original or Lords of the North, but these spells are very powerful. Tomes of magic of 4 schools also appeared only in Lords of the North.
Okay, I got carried away with my unnecessary story
In general, yes, there are many interesting things that can be changed there, and you don't even need much knowledge. These things are intuitively understandable. Just click around with the keywords, and I think you will quickly find a lot of interesting things. If you need it.