[MOD] Scenarios and campaigns: original, Hammers of Fate.

Hello everyone! I sincerely apologize for bringing up such an old topic from the "depths," but I don't know where else to turn with my question. The issue is this: in the campaigns and scenarios mentioned above, both the original game and Hammers of Fate have a small but rather unpleasant flaw – in the fortress on the hill, it's impossible to switch creatures from the main upgraded version to the alternative version and back (which is quite strange, considering that the freedom to choose the upgrade is preserved). I would like to know what causes this and how it can be fixed. I also reiterate the question from a user at the beginning of the thread, who never received an answer:

there's one problem: assembled artifacts don't carry over from one mission to another. Is there any way to fix this?