DISCUSSIONS on “Rules for online games in HoMM3 and formulas for calculating player rating.”

No way.

"Izra and Vidomina, who gained the Expert Spellcasting skill through a method different from the one specified in section 5.10.2...."

Izra and Vidomina, who escaped from prison, gained Expert Spellcasting through a method different from the one specified in section 5.10.2.
That is, strictly following the RULES, they cannot be used.

And I insist that it is not at all a given that allowing them to be used in this situation is self-evident (although I personally agree that they can be used) - but the fact remains that it is much easier to free an overpowered hero from prison than to develop them independently!!!
And the purpose of the rule was to limit this overpoweredness. Another question is what exactly was meant.

And since I myself am a dedicated Warlord player, where necromancy is completely disabled, I am not capable of understanding these nuances. This rule is a workaround. No matter how you phrase it, it's still a clumsy workaround. Relying on common sense, it is still impossible to understand anything (think about it - in Warlord, even with necromancy disabled, the undead still consistently remain in the top 3 factions, and with it enabled in Stronghold, I have repeatedly seen players simply switch to the undead).
Common sense has not yet prevailed in this rule, so it simply needs to be reformulated to avoid ambiguity.