Justice is a fan-made global mod.

Enough guessing – everything has already been described: the Titans of Ashan are mechanisms; they are alive only in Heroes 5, and as is well known, Heroes 5 contradicts Heroes 6 and 7 in terms of lore.

Or you can read it the other way around: Heroes 6 and 7, as is well known, contradict Heroes 5 in terms of lore, therefore, it is not canon. It's up to each person to decide what they prefer. I believe that the law of the strong applies, and the stronger part has more authority. But if you really want to justify making the Titans mechanical, using the lore of other games, in particular Heroes 6, 7, or some other game from another series, why not?
The problem is that regeneration/resurrection stops working for the mechanics, which means a minus for the strategy of regenerating/resurrecting Titans. From a gameplay perspective, this option leaves fewer choices.