Posts from Legal aspects of modding.

Technically, it is possible to use assets from Heroes 7. Moreover, it is much easier than using assets from Heroes 6, because Heroes 7 was made on Unreal Engine, and they didn't put much effort into it. This means that you can easily extract models, textures, and skeletons with animations from the game. It's a pity that you can't directly import the skeletons with animations into Heroes 5, and you'll still have to adapt them to the native skeletons of Heroes 5, plus, again, you'll have to reduce the polygon count. But from a legal point of view, I'm not entirely sure. It seems that as long as you don't sell these assets, it's okay, but it also seems that it might not be. However, in order for someone to sue you, it has to be something that concerns them enough to warrant a lawsuit. It's unlikely that Ubisoft will take any action over a couple of models. And there are many examples on the internet of assets from one game being used in other games, and these games are often less related to each other than Heroes 5, 6, and 7. In general, it's a gray area; it seems like you can do it, but maybe you can't. That is, Ubisoft always has the option to take action, but the question is whether they want to, especially considering their level of interest in the Heroes series. Even regarding Heroes 6, it's not entirely clear. It seems that it was said that assets from Heroes 6 can be used for Heroes 5. But who gave this permission? And is there any guarantee that this permission has any legal force, or is it just something that will be forgotten in the event of a dispute? Ideally, of course, it would be great and more interesting to do everything from scratch, not to use assets from Heroes 6, 7, etc., but to reach that level ourselves. But firstly, this is much less in demand because most people want to see "how it looks," and secondly, it's much more difficult and time-consuming.

Did Ubisoft give permission? I don't think so, not without proof. Modern Ubisoft never gives permission for anything, at least not for free.

Added 1 minute later
And remembering that guy who supposedly talked to some Ubisoft employee about mods and how it all ended...

Since the support team has already started writing to me, claiming that using the map editor for Heroes 5 is illegal.

O_o
What about the "consumer protection law"? If they don't allow the use of one of the game's built-in features, they should refund the money and pay a penalty...
There's one fundamental thing to understand when communicating with them. All these rules they come up with are just nonsense. Copyright restricts the sale and distribution of content; everything else is just fantasy. Even if such clauses are included in the license agreement (and I don't believe that the Heroes 5 license agreement contains a clause prohibiting modifications after the release of the next game), it doesn't have any legal force, according to the laws of any country.

The support refers to point 3.1, stating that Heroes 5 falls under the category of services, and the new Ubisoft license is general for all products, superseding old licenses.

In this regard, you confirm your agreement that UBISOFT will be the sole copyright holder with respect to the User-Generated Content (UGC) created by you using previously created UBISOFT Content, when and as such UGC is created by you.