Heroes 5.5 WarGame Edition - Tactical Edition.

3. I thought it was a bug because in Inferno, ifrits were recruited, and in the Academy, abyssal demons were recruited; it needs to be changed.

If you are using the NCF mod in parallel, this is possible. You need to resolve the conflict between the two files with a list of unit IDs (I don't remember the exact file names) for ifrits and balors, taking the values from WGE.

4. Then their morale drops; it's better to give ifrits courage (they want to fight and kill), and somehow fix the morale of the jinn at zero. Would these changes work?

That's exactly why in the new version, all 3 jinn will be neutral (as part of only the Academy's troops, they will all have a base morale of 0 instead of +2, and the rest will have +1 instead of +2).
The neutrality/demonism of jinn/ifrits are special features (negative for the Academy). But we will have to abandon demonism, as people don't like negative morale. Although the courage option is also interesting.